diff --git a/src/app/api/constants.ts b/src/app/api/constants.ts
deleted file mode 100644
index 341d75978..000000000
--- a/src/app/api/constants.ts
+++ /dev/null
@@ -1,20 +0,0 @@
-/***********************************************************
- * Copyright (c) Microsoft Corporation. All rights reserved.
- * Licensed under the MIT License
- **********************************************************/
-export enum HTTP_OPERATION_TYPES {
-    Delete = 'DELETE',
-    Get = 'GET',
-    Patch = 'PATCH',
-    Post = 'POST',
-    Put = 'PUT'
-}
-
-export const MILLISECONDS_PER_SECOND = 1000;
-export const SECONDS_PER_MINUTE = 60;
-export const APPLICATION_JSON = 'application/json';
-export const ERROR_TYPES = {
-    AUTHORIZATION_RULE_NOT_FOUND: 'authorizationRuleNotFound',
-    HTTP: 'http',
-    PORT_IS_IN_USE: 'portIsInUse'
-};
diff --git a/src/app/api/models/authorizationRuleNotFoundError.ts b/src/app/api/models/authorizationRuleNotFoundError.ts
index d13a73a67..e01c431f2 100644
--- a/src/app/api/models/authorizationRuleNotFoundError.ts
+++ b/src/app/api/models/authorizationRuleNotFoundError.ts
@@ -2,7 +2,7 @@
  * Copyright (c) Microsoft Corporation. All rights reserved.
  * Licensed under the MIT License
  **********************************************************/
-import { ERROR_TYPES } from '../constants';
+import { ERROR_TYPES } from './../../constants/apiConstants';
 
 export class AuthorizationRuleNotFoundError extends Error {
     public requiredPermissions: string[];
diff --git a/src/app/api/models/httpError.ts b/src/app/api/models/httpError.ts
index bc5c6226a..d8762bff3 100644
--- a/src/app/api/models/httpError.ts
+++ b/src/app/api/models/httpError.ts
@@ -2,7 +2,7 @@
  * Copyright (c) Microsoft Corporation. All rights reserved.
  * Licensed under the MIT License
  **********************************************************/
-import { ERROR_TYPES } from '../constants';
+import { ERROR_TYPES } from './../../constants/apiConstants';
 
 export class HttpError extends Error {
     public httpCode: number;
diff --git a/src/app/api/models/modelDefinitionWithSource.ts b/src/app/api/models/modelDefinitionWithSource.ts
index ae649f560..78e1863b6 100644
--- a/src/app/api/models/modelDefinitionWithSource.ts
+++ b/src/app/api/models/modelDefinitionWithSource.ts
@@ -7,5 +7,6 @@ import { REPOSITORY_LOCATION_TYPE } from '../../constants/repositoryLocationType
 
 export interface ModelDefinitionWithSource {
     modelDefinition: ModelDefinition;
-    source?: REPOSITORY_LOCATION_TYPE;
+    source: REPOSITORY_LOCATION_TYPE;
+    isModelValid: boolean;
 }
diff --git a/src/app/api/models/portIsInUseError.ts b/src/app/api/models/portIsInUseError.ts
index 73dc39b71..9f3525931 100644
--- a/src/app/api/models/portIsInUseError.ts
+++ b/src/app/api/models/portIsInUseError.ts
@@ -2,7 +2,7 @@
  * Copyright (c) Microsoft Corporation. All rights reserved.
  * Licensed under the MIT License
  **********************************************************/
-import { ERROR_TYPES } from '../constants';
+import { ERROR_TYPES } from './../../constants/apiConstants';
 
 export class PortIsInUseError extends Error {
     constructor() {
diff --git a/src/app/api/services/dataplaneServiceHelper.ts b/src/app/api/services/dataplaneServiceHelper.ts
index c42b57d18..17858b6c1 100644
--- a/src/app/api/services/dataplaneServiceHelper.ts
+++ b/src/app/api/services/dataplaneServiceHelper.ts
@@ -3,8 +3,7 @@
  * Licensed under the MIT License
  **********************************************************/
 import { DataPlaneParameters } from '../parameters/deviceParameters';
-import { CONTROLLER_API_ENDPOINT, DATAPLANE, DataPlaneStatusCode } from '../../constants/apiConstants';
-import { HTTP_OPERATION_TYPES } from '../constants';
+import { CONTROLLER_API_ENDPOINT, DATAPLANE, DataPlaneStatusCode, HTTP_OPERATION_TYPES } from '../../constants/apiConstants';
 import { getConnectionInfoFromConnectionString, generateSasToken } from '../shared/utils';
 import { PortIsInUseError } from '../models/portIsInUseError';
 
diff --git a/src/app/api/services/devicesService.spec.ts b/src/app/api/services/devicesService.spec.ts
index 9bea7778a..29810a854 100644
--- a/src/app/api/services/devicesService.spec.ts
+++ b/src/app/api/services/devicesService.spec.ts
@@ -5,8 +5,7 @@
 import 'jest';
 import * as DevicesService from './devicesService';
 import * as DataplaneService from './dataplaneServiceHelper';
-import { HTTP_OPERATION_TYPES } from '../constants';
-import { DIGITAL_TWIN_API_VERSION, CONTROLLER_API_ENDPOINT, CLOUD_TO_DEVICE } from '../../constants/apiConstants';
+import { DIGITAL_TWIN_API_VERSION, CONTROLLER_API_ENDPOINT, CLOUD_TO_DEVICE, HTTP_OPERATION_TYPES } from '../../constants/apiConstants';
 import { CONNECTION_TIMEOUT_IN_SECONDS, RESPONSE_TIME_IN_SECONDS } from '../../constants/devices';
 import { Twin } from '../models/device';
 import { DeviceIdentity } from './../models/deviceIdentity';
diff --git a/src/app/api/services/devicesService.ts b/src/app/api/services/devicesService.ts
index 3ec70203c..d88834bcc 100644
--- a/src/app/api/services/devicesService.ts
+++ b/src/app/api/services/devicesService.ts
@@ -17,8 +17,7 @@ import {
     PatchDigitalTwinInterfacePropertiesParameters,
     CloudToDeviceMessageParameters
 } from '../parameters/deviceParameters';
-import { CONTROLLER_API_ENDPOINT, EVENTHUB, DIGITAL_TWIN_API_VERSION, MONITOR, STOP, HEADERS, CLOUD_TO_DEVICE } from '../../constants/apiConstants';
-import { HTTP_OPERATION_TYPES } from '../constants';
+import { CONTROLLER_API_ENDPOINT, EVENTHUB, DIGITAL_TWIN_API_VERSION, MONITOR, STOP, HEADERS, CLOUD_TO_DEVICE, HTTP_OPERATION_TYPES } from '../../constants/apiConstants';
 import { buildQueryString } from '../shared/utils';
 import { CONNECTION_TIMEOUT_IN_SECONDS, RESPONSE_TIME_IN_SECONDS } from '../../constants/devices';
 import { Message } from '../models/messages';
diff --git a/src/app/api/services/digitalTwinsModelService.spec.ts b/src/app/api/services/digitalTwinsModelService.spec.ts
index 0ad62af06..b7b488910 100644
--- a/src/app/api/services/digitalTwinsModelService.spec.ts
+++ b/src/app/api/services/digitalTwinsModelService.spec.ts
@@ -3,8 +3,7 @@
  * Licensed under the MIT License
  **********************************************************/
 import * as DigitalTwinsModelService from './digitalTwinsModelService';
-import { API_VERSION, DIGITAL_TWIN_API_VERSION } from '../../constants/apiConstants';
-import { HTTP_OPERATION_TYPES } from '../constants';
+import { API_VERSION, DIGITAL_TWIN_API_VERSION, MODEL_REPO_API_VERSION, HTTP_OPERATION_TYPES, PUBLIC_REPO_HOSTNAME_TEST } from '../../constants/apiConstants';
 
 describe('digitalTwinsModelService', () => {
 
@@ -111,4 +110,46 @@ describe('digitalTwinsModelService', () => {
             done();
         });
     });
+
+    context('validateModelDefinitions', () => {
+        const parameters = JSON.stringify([]);
+
+        it('calls fetch with specified parameters and returns true when response is 200', async () => {
+            // tslint:disable
+            const response = {
+                json: () => {},
+                ok: true
+            } as any;
+            // tslint:enable
+            jest.spyOn(window, 'fetch').mockResolvedValue(response);
+
+            const result = await DigitalTwinsModelService.validateModelDefinitions(parameters);
+
+            const apiVersionQueryString = `?${API_VERSION}${MODEL_REPO_API_VERSION}`;
+            const controllerRequest = {
+                body: parameters,
+                headers: {
+                    'Accept': 'application/json',
+                    'Content-Type': 'application/json',
+                    'x-ms-client-request-id': 'azure iot explorer: validate model definition'
+                },
+                method: HTTP_OPERATION_TYPES.Post,
+                uri: `https://${PUBLIC_REPO_HOSTNAME_TEST}/models/validate${apiVersionQueryString}`
+            };
+
+            const validateModelParameters = {
+                body: JSON.stringify(controllerRequest),
+                cache: 'no-cache',
+                credentials: 'include',
+                headers: new Headers({
+                    'Accept': 'application/json',
+                    'Content-Type': 'application/json'
+                }),
+                method: HTTP_OPERATION_TYPES.Post
+            };
+
+            expect(fetch).toBeCalledWith(DigitalTwinsModelService.CONTROLLER_ENDPOINT, validateModelParameters);
+            expect(result).toEqual(true);
+        });
+    });
 });
diff --git a/src/app/api/services/digitalTwinsModelService.ts b/src/app/api/services/digitalTwinsModelService.ts
index 4972fa39d..c04d94d16 100644
--- a/src/app/api/services/digitalTwinsModelService.ts
+++ b/src/app/api/services/digitalTwinsModelService.ts
@@ -9,8 +9,10 @@ import {
     CONTROLLER_API_ENDPOINT,
     DIGITAL_TWIN_API_VERSION,
     HEADERS,
-    MODELREPO } from '../../constants/apiConstants';
-import { HTTP_OPERATION_TYPES } from '../constants';
+    MODELREPO,
+    MODEL_REPO_API_VERSION,
+    PUBLIC_REPO_HOSTNAME_TEST,
+    HTTP_OPERATION_TYPES } from '../../constants/apiConstants';
 import { PnPModel } from '../models/metamodelMetadata';
 
 export const fetchModel = async (parameters: FetchModelParameters): Promise<PnPModel> => {
@@ -69,6 +71,27 @@ export const fetchModelDefinition = async (parameters: FetchModelParameters) =>
     }
 };
 
+export const validateModelDefinitions = async (modelDefinitions: string) => {
+    try {
+        const apiVersionQueryString = `?${API_VERSION}${MODEL_REPO_API_VERSION}`;
+        const controllerRequest: RequestInitWithUri = {
+            body: modelDefinitions,
+            headers: {
+                'Accept': 'application/json',
+                'Content-Type': 'application/json',
+                'x-ms-client-request-id': 'azure iot explorer: validate model definition'
+            },
+            method: HTTP_OPERATION_TYPES.Post,
+            uri: `https://${PUBLIC_REPO_HOSTNAME_TEST}/models/validate${apiVersionQueryString}`
+        };
+
+        return (await request(controllerRequest)).ok;
+    }
+    catch (error) {
+        throw new Error(error);
+    }
+};
+
 export interface RequestInitWithUri extends RequestInit {
     uri: string;
     headers?: Record<string, string>;
@@ -82,6 +105,7 @@ export interface RepoConnectionSettings {
 }
 
 export const CONTROLLER_ENDPOINT = `${CONTROLLER_API_ENDPOINT}${MODELREPO}`;
+
 const request = async (requestInit: RequestInitWithUri) => {
     return fetch(
         CONTROLLER_ENDPOINT,
diff --git a/src/app/api/services/moduleService.spec.ts b/src/app/api/services/moduleService.spec.ts
index f375f0afd..cadffb043 100644
--- a/src/app/api/services/moduleService.spec.ts
+++ b/src/app/api/services/moduleService.spec.ts
@@ -5,11 +5,11 @@
 import 'jest';
 import * as ModuleService from './moduleService';
 import * as DataplaneService from './dataplaneServiceHelper';
-import { HTTP_OPERATION_TYPES } from '../constants';
 import { getConnectionInfoFromConnectionString } from '../shared/utils';
 import { DataPlaneParameters } from '../parameters/deviceParameters';
 import { ModuleIdentity } from '../models/moduleIdentity';
 import { ModuleTwin } from '../models/moduleTwin';
+import { HTTP_OPERATION_TYPES } from '../../constants/apiConstants';
 
 const deviceId = 'deviceId';
 const moduleId = 'moduleId';
diff --git a/src/app/api/services/moduleService.ts b/src/app/api/services/moduleService.ts
index bdd68dbb4..1568df64c 100644
--- a/src/app/api/services/moduleService.ts
+++ b/src/app/api/services/moduleService.ts
@@ -8,12 +8,11 @@ import {
     ModuleIdentityTwinParameters,
     FetchModuleIdentityParameters
 } from '../parameters/moduleParameters';
-import { HTTP_OPERATION_TYPES } from '../constants';
 import { DataPlaneResponse } from '../models/device';
 import { ModuleIdentity } from '../models/moduleIdentity';
 import { ModuleTwin } from '../models/moduleTwin';
 import { dataPlaneConnectionHelper, dataPlaneResponseHelper, request, DATAPLANE_CONTROLLER_ENDPOINT, DataPlaneRequest } from './dataplaneServiceHelper';
-import { HEADERS } from '../../constants/apiConstants';
+import { HEADERS, HTTP_OPERATION_TYPES } from '../../constants/apiConstants';
 
 export interface IoTHubConnectionSettings {
     hostName?: string;
diff --git a/src/app/api/shared/utils.ts b/src/app/api/shared/utils.ts
index 55a45002b..7ea7daa02 100644
--- a/src/app/api/shared/utils.ts
+++ b/src/app/api/shared/utils.ts
@@ -7,8 +7,7 @@ import { IoTHubConnectionSettings } from '../services/devicesService';
 import { LIST_PLUG_AND_PLAY_DEVICES, SAS_EXPIRES_MINUTES } from '../../constants/devices';
 import DeviceQuery, { QueryClause, ParameterType, OperationType } from '../models/deviceQuery';
 import { RepoConnectionSettings } from '../services/digitalTwinsModelService';
-import { AppEnvironment } from '../../constants/shared';
-import { MILLISECONDS_PER_SECOND, SECONDS_PER_MINUTE } from '../constants';
+import { AppEnvironment, MILLISECONDS_PER_SECOND, SECONDS_PER_MINUTE } from '../../constants/shared';
 
 export const enum PnPQueryPrefix {
     HAS_CAPABILITY_MODEL = 'HAS_CAPABILITYMODEL',
diff --git a/src/app/azureResourceIdentifier/services/azureResourceIdentifierService.spec.ts b/src/app/azureResourceIdentifier/services/azureResourceIdentifierService.spec.ts
index 5603fe34a..425d3473a 100644
--- a/src/app/azureResourceIdentifier/services/azureResourceIdentifierService.spec.ts
+++ b/src/app/azureResourceIdentifier/services/azureResourceIdentifierService.spec.ts
@@ -5,7 +5,7 @@
 import { getAzureResourceIdentifiers, getAzureResourceIdentifier } from './azureResourceIdentifierService';
 import { AzureResourceIdentifierType } from '../models/azureResourceIdentifierType';
 import { HttpError } from '../../api/models/httpError';
-import { APPLICATION_JSON, HTTP_OPERATION_TYPES } from '../../api/constants';
+import { HTTP_OPERATION_TYPES, APPLICATION_JSON } from '../../constants/apiConstants';
 
 describe('getAzureResourceIdentifiers', () => {
     it('calls fetch with specificed parameters', () => {
diff --git a/src/app/azureResourceIdentifier/services/azureResourceIdentifierService.ts b/src/app/azureResourceIdentifier/services/azureResourceIdentifierService.ts
index c0aba0b1e..46e312fc1 100644
--- a/src/app/azureResourceIdentifier/services/azureResourceIdentifierService.ts
+++ b/src/app/azureResourceIdentifier/services/azureResourceIdentifierService.ts
@@ -7,7 +7,7 @@ import { AzureResourceIdentifier } from '../models/azureResourceIdentifier';
 import { AzureResourceIdentifierType } from '../models/azureResourceIdentifierType';
 import { AzureResourceIdentifierQuery } from '../models/azureResourceIdentifierQuery';
 import { AzureResourceIdentifierQueryResult } from '../models/azureResourceIdentifierQueryResult';
-import { APPLICATION_JSON, HTTP_OPERATION_TYPES } from '../../api/constants';
+import { APPLICATION_JSON, HTTP_OPERATION_TYPES } from '../../constants/apiConstants';
 import { AzureResourceManagementEndpoint } from '../models/azureResourceManagementEndpoint';
 import { HttpError } from '../../api/models/httpError';
 import { mapPropertyArrayToObject } from '../../api/shared/mapUtils';
diff --git a/src/app/azureResourceIdentifier/services/azureSubscriptionService.spec.ts b/src/app/azureResourceIdentifier/services/azureSubscriptionService.spec.ts
index c6d82e8f5..b73ea29c3 100644
--- a/src/app/azureResourceIdentifier/services/azureSubscriptionService.spec.ts
+++ b/src/app/azureResourceIdentifier/services/azureSubscriptionService.spec.ts
@@ -1,10 +1,11 @@
+import { HTTP_OPERATION_TYPES } from './../../constants/apiConstants';
 /***********************************************************
  * Copyright (c) Microsoft Corporation. All rights reserved.
  * Licensed under the MIT License
  **********************************************************/
 import { getAzureSubscriptions } from './azureSubscriptionService';
 import { HttpError } from '../../api/models/httpError';
-import { APPLICATION_JSON, HTTP_OPERATION_TYPES } from '../../api/constants';
+import { APPLICATION_JSON } from '../../constants/apiConstants';
 
 describe('getAzureSubscriptions', () => {
     it('calls fetch with expected parameters', () => {
diff --git a/src/app/azureResourceIdentifier/services/azureSubscriptionService.ts b/src/app/azureResourceIdentifier/services/azureSubscriptionService.ts
index 2c7cc85b4..3ac8f9826 100644
--- a/src/app/azureResourceIdentifier/services/azureSubscriptionService.ts
+++ b/src/app/azureResourceIdentifier/services/azureSubscriptionService.ts
@@ -3,7 +3,7 @@
  * Licensed under the MIT License
  **********************************************************/
 import { AzureResourceManagementEndpoint } from '../models/azureResourceManagementEndpoint';
-import { APPLICATION_JSON, HTTP_OPERATION_TYPES } from '../../api/constants';
+import { APPLICATION_JSON, HTTP_OPERATION_TYPES } from '../../constants/apiConstants';
 import { HttpError } from '../../api/models/httpError';
 import { AzureSubscription } from '../models/azureSubscription';
 
diff --git a/src/app/constants/apiConstants.ts b/src/app/constants/apiConstants.ts
index 8e390c056..0e118980d 100644
--- a/src/app/constants/apiConstants.ts
+++ b/src/app/constants/apiConstants.ts
@@ -20,6 +20,8 @@ export const MODEL_ID_REF = '/ref:modelId?';
 export const MODEL_ID = 'modelId=';
 export const API_VERSION = 'api-version=';
 export const AND = '&';
+export const PUBLIC_REPO_HOSTNAME = 'repo.azureiotrepository.com';
+export const PUBLIC_REPO_HOSTNAME_TEST = 'repo.azureiotrepository-test.com';
 
 // event hub controller
 export const MONITOR = '/monitor';
@@ -27,6 +29,7 @@ export const STOP = '/stop';
 
 // digital twin api version
 export const DIGITAL_TWIN_API_VERSION = '2019-07-01-preview';
+export const MODEL_REPO_API_VERSION = '2020-05-01-preview';
 
 export const HEADERS = {
     CONTINUATION_TOKEN: 'x-ms-continuation',
@@ -56,3 +59,18 @@ export const CONTROLLER_API_ENDPOINT =
     appConfig.hostMode ===  HostMode.Browser ?
         `${localIp}:${appConfig.controllerPort}${apiPath}` :
         `${localIp}:${localStorage.getItem(CUSTOM_CONTROLLER_PORT) || appConfig.controllerPort}${apiPath}`;
+
+export enum HTTP_OPERATION_TYPES {
+    Delete = 'DELETE',
+    Get = 'GET',
+    Patch = 'PATCH',
+    Post = 'POST',
+    Put = 'PUT'
+}
+
+export const APPLICATION_JSON = 'application/json';
+export const ERROR_TYPES = {
+    AUTHORIZATION_RULE_NOT_FOUND: 'authorizationRuleNotFound',
+    HTTP: 'http',
+    PORT_IS_IN_USE: 'portIsInUse'
+};
diff --git a/src/app/constants/shared.ts b/src/app/constants/shared.ts
index 1665b6ad3..edbd3fc20 100644
--- a/src/app/constants/shared.ts
+++ b/src/app/constants/shared.ts
@@ -2,21 +2,10 @@
  * Copyright (c) Microsoft Corporation. All rights reserved.
  * Licensed under the MIT License
  **********************************************************/
-export enum SYNC_STATUS {
-    Failed,
-    None,
-    Synced,
-    Syncing
-}
-
-export enum DesiredStateStatus{
-    Success = 200,
-    Synching = 202,
-    Error = 500
-}
-
+export const OFFSET_IN_MINUTES = 15;
 export const MILLISECONDS_IN_MINUTE = 60000;
-export const PUBLIC_REPO_HOSTNAME = 'repo.azureiotrepository.com';
+export const MILLISECONDS_PER_SECOND = 1000;
+export const SECONDS_PER_MINUTE = 60;
 
 export enum AppEnvironment {
     ProdElectron = 'prodElectron',
diff --git a/src/app/devices/deviceContent/actions.ts b/src/app/devices/deviceContent/actions.ts
index 847c176c1..ed788074e 100644
--- a/src/app/devices/deviceContent/actions.ts
+++ b/src/app/devices/deviceContent/actions.ts
@@ -5,11 +5,10 @@
 import actionCreatorFactory from 'typescript-fsa';
 import * as actionPrefixes from '../../constants/actionPrefixes';
 import * as actionTypes from '../../constants/actionTypes';
-import { ModelDefinition } from '../../api/models/modelDefinition';
 import { Twin } from '../../api/models/device';
 import { DeviceIdentity } from '../../api/models/deviceIdentity';
 import { DigitalTwinInterfaces } from './../../api/models/digitalTwinModels';
-import { REPOSITORY_LOCATION_TYPE } from './../../constants/repositoryLocationTypes';
+import { ModelDefinitionWithSource } from './../../api/models/modelDefinitionWithSource';
 
 const deviceContentCreator = actionCreatorFactory(actionPrefixes.DEVICECONTENT);
 const clearModelDefinitionsAction = deviceContentCreator(actionTypes.CLEAR_MODEL_DEFINITIONS);
@@ -17,7 +16,7 @@ const cloudToDeviceMessageAction = deviceContentCreator.async<CloudToDeviceMessa
 const getDeviceIdentityAction = deviceContentCreator.async<string, DeviceIdentity> (actionTypes.GET_DEVICE_IDENTITY);
 const getDigitalTwinInterfacePropertiesAction = deviceContentCreator.async<string, DigitalTwinInterfaces>(actionTypes.GET_DIGITAL_TWIN_INTERFACE_PROPERTIES);
 const getTwinAction = deviceContentCreator.async<string, Twin>(actionTypes.GET_TWIN);
-const getModelDefinitionAction = deviceContentCreator.async<GetModelDefinitionActionParameters, ModelDefinitionActionResult>(actionTypes.FETCH_MODEL_DEFINITION);
+const getModelDefinitionAction = deviceContentCreator.async<GetModelDefinitionActionParameters, ModelDefinitionWithSource>(actionTypes.FETCH_MODEL_DEFINITION);
 const invokeDirectMethodAction = deviceContentCreator.async<InvokeMethodActionParameters, string>(actionTypes.INVOKE_DEVICE_METHOD);
 const invokeDigitalTwinInterfaceCommandAction = deviceContentCreator.async<InvokeDigitalTwinInterfaceCommandActionParameters, string>(actionTypes.INVOKE_DIGITAL_TWIN_INTERFACE_COMMAND);
 const patchDigitalTwinInterfacePropertiesAction = deviceContentCreator.async<PatchDigitalTwinInterfacePropertiesActionParameters, DigitalTwinInterfaces>(actionTypes.PATCH_DIGITAL_TWIN_INTERFACE_PROPERTIES);
@@ -71,11 +70,6 @@ export interface UpdateTwinActionParameters {
     twin: Twin;
 }
 
-export interface ModelDefinitionActionResult {
-    modelDefinition: ModelDefinition;
-    source: REPOSITORY_LOCATION_TYPE;
-}
-
 export interface GetModelDefinitionActionParameters {
     digitalTwinId: string;
     interfaceId: string;
diff --git a/src/app/devices/deviceContent/components/deviceInterfaces/__snapshots__/deviceInterfaces.spec.tsx.snap b/src/app/devices/deviceContent/components/deviceInterfaces/__snapshots__/deviceInterfaces.spec.tsx.snap
index 7fc9f6b89..0b6112ee8 100644
--- a/src/app/devices/deviceContent/components/deviceInterfaces/__snapshots__/deviceInterfaces.spec.tsx.snap
+++ b/src/app/devices/deviceContent/components/deviceInterfaces/__snapshots__/deviceInterfaces.spec.tsx.snap
@@ -471,47 +471,14 @@ exports[`components/devices/deviceInterfaces shows interface information when st
   <ErrorBoundary
     error="errorBoundary.text"
   >
-    <Route
-      component={[Function]}
-    />
     <section
       className="pnp-interface-info scrollable-lg"
     >
-      <StyledLabelBase
-        className="source"
-      >
-         
-        deviceInterfaces.columns.source
-        : 
-        --
-      </StyledLabelBase>
-      <CustomizedActionButton
-        className="configure-button"
-        onClick={[Function]}
+      <StyledMessageBarBase
+        messageBarType={1}
       >
-        deviceInterfaces.command.configure
-      </CustomizedActionButton>
-      <Connect(MaskedCopyableTextField)
-        allowMask={false}
-        ariaLabel="deviceInterfaces.columns.id"
-        label="deviceInterfaces.columns.id"
-        readOnly={true}
-        value={null}
-      />
-      <Connect(MaskedCopyableTextField)
-        allowMask={false}
-        ariaLabel="deviceInterfaces.columns.displayName"
-        label="deviceInterfaces.columns.displayName"
-        readOnly={true}
-        value="--"
-      />
-      <Connect(MaskedCopyableTextField)
-        allowMask={false}
-        ariaLabel="deviceInterfaces.columns.description"
-        label="deviceInterfaces.columns.description"
-        readOnly={true}
-        value="--"
-      />
+        deviceInterfaces.interfaceNotValid
+      </StyledMessageBarBase>
       <article
         className="interface-definition"
       >
diff --git a/src/app/devices/deviceContent/components/deviceInterfaces/deviceInterfaces.spec.tsx b/src/app/devices/deviceContent/components/deviceInterfaces/deviceInterfaces.spec.tsx
index c0ed904d2..0c00536bd 100644
--- a/src/app/devices/deviceContent/components/deviceInterfaces/deviceInterfaces.spec.tsx
+++ b/src/app/devices/deviceContent/components/deviceInterfaces/deviceInterfaces.spec.tsx
@@ -112,6 +112,7 @@ describe('components/devices/deviceInterfaces', () => {
             isLoading: false,
             modelDefinitionWithSource: {
                 payload: {
+                    isModelValid: true,
                     modelDefinition,
                     source: REPOSITORY_LOCATION_TYPE.Public,
                 },
@@ -129,6 +130,7 @@ describe('components/devices/deviceInterfaces', () => {
             isLoading: false,
             modelDefinitionWithSource: {
                 payload: {
+                    isModelValid: true,
                     modelDefinition,
                     source: REPOSITORY_LOCATION_TYPE.Private,
                 },
@@ -141,6 +143,7 @@ describe('components/devices/deviceInterfaces', () => {
             isLoading: false,
             modelDefinitionWithSource: {
                 payload: {
+                    isModelValid: true,
                     modelDefinition,
                     source: REPOSITORY_LOCATION_TYPE.Device,
                 },
@@ -153,6 +156,7 @@ describe('components/devices/deviceInterfaces', () => {
             isLoading: false,
             modelDefinitionWithSource: {
                 payload: {
+                    isModelValid: true,
                     modelDefinition,
                     source: REPOSITORY_LOCATION_TYPE.Local
                 },
@@ -165,6 +169,7 @@ describe('components/devices/deviceInterfaces', () => {
             isLoading: false,
             modelDefinitionWithSource: {
                 payload: {
+                    isModelValid: false,
                     modelDefinition,
                     source: undefined
                 },
diff --git a/src/app/devices/deviceContent/components/deviceInterfaces/deviceInterfaces.tsx b/src/app/devices/deviceContent/components/deviceInterfaces/deviceInterfaces.tsx
index 6dc5b3f1d..9a1f16f36 100644
--- a/src/app/devices/deviceContent/components/deviceInterfaces/deviceInterfaces.tsx
+++ b/src/app/devices/deviceContent/components/deviceInterfaces/deviceInterfaces.tsx
@@ -7,6 +7,10 @@ import { Label } from 'office-ui-fabric-react/lib/Label';
 import { CommandBar } from 'office-ui-fabric-react/lib/CommandBar';
 import { ActionButton } from 'office-ui-fabric-react/lib/Button';
 import { Spinner, SpinnerSize } from 'office-ui-fabric-react/lib/Spinner';
+import {
+    MessageBar,
+    MessageBarType,
+} from 'office-ui-fabric-react';
 import { RouteComponentProps, Route } from 'react-router-dom';
 import { LocalizationContextConsumer, LocalizationContextInterface } from '../../../../shared/contexts/localizationContext';
 import { ResourceKeys } from '../../../../../localization/resourceKeys';
@@ -88,11 +92,23 @@ export default class DeviceInterfaces extends React.Component<DeviceInterfacePro
             <>
                 {modelDefinitionWithSource && modelDefinitionWithSource.payload ?
                     <ErrorBoundary error={context.t(ResourceKeys.errorBoundary.text)}>
-                        <Route component={DigitalTwinHeaderContainer} />
-                        <section className="pnp-interface-info scrollable-lg">
-                            {this.renderInterfaceInfoDetail(context)}
-                            {this.renderInterfaceViewer()}
-                        </section>
+                        {modelDefinitionWithSource.payload.isModelValid ?
+                            <>
+                                <Route component={DigitalTwinHeaderContainer} />
+                                <section className="pnp-interface-info scrollable-lg">
+                                    {this.renderInterfaceInfoDetail(context)}
+                                    {this.renderInterfaceViewer()}
+                                </section>
+                            </> :
+                            <section className="pnp-interface-info scrollable-lg">
+                                <MessageBar
+                                    messageBarType={MessageBarType.error}
+                                >
+                                    {context.t(ResourceKeys.deviceInterfaces.interfaceNotValid)}
+                                </MessageBar>
+                                {this.renderInterfaceViewer()}
+                            </section>
+                        }
                     </ErrorBoundary> :
                     <InterfaceNotFoundMessageBoxContainer/>
                 }
diff --git a/src/app/devices/deviceContent/components/shared/desiredStateStatus.tsx b/src/app/devices/deviceContent/components/shared/desiredStateStatus.tsx
index 1137fbda3..859f6e29c 100644
--- a/src/app/devices/deviceContent/components/shared/desiredStateStatus.tsx
+++ b/src/app/devices/deviceContent/components/shared/desiredStateStatus.tsx
@@ -9,7 +9,12 @@ import LabelWithTooltip from '../../../../shared/components/labelWithTooltip';
 import { LocalizationContextConsumer, LocalizationContextInterface } from '../../../..//shared/contexts/localizationContext';
 import { ResourceKeys } from '../../../../../localization/resourceKeys';
 import { ACCEPT, WARNING, SYNCH } from '../../../../constants/iconNames';
-import { DesiredStateStatus } from '../../../../constants/shared';
+
+export enum DesiredStateStatus{
+    Success = 200,
+    Synching = 202,
+    Error = 500
+}
 
 export const RenderDesiredState = (state: DesiredState) => {
     return (
diff --git a/src/app/devices/deviceContent/reducer.spec.ts b/src/app/devices/deviceContent/reducer.spec.ts
index eca62ccbe..313826fd6 100644
--- a/src/app/devices/deviceContent/reducer.spec.ts
+++ b/src/app/devices/deviceContent/reducer.spec.ts
@@ -75,6 +75,7 @@ describe('deviceContentStateReducer', () => {
         /* tslint:enable */
         const modelDefinitionWithSource = {
             payload: {
+                isModelValid: true,
                 modelDefinition,
                 source: REPOSITORY_LOCATION_TYPE.Public
             },
@@ -87,9 +88,14 @@ describe('deviceContentStateReducer', () => {
         });
 
         it (`handles ${FETCH_MODEL_DEFINITION}/ACTION_DONE action`, () => {
-            const action = getModelDefinitionAction.done({params: {digitalTwinId: 'testDevice', interfaceId: 'urn:azureiot:ModelDiscovery:ModelInformation:1'}, result: {modelDefinition, source: REPOSITORY_LOCATION_TYPE.Public }});
+            const action = getModelDefinitionAction.done(
+                {
+                    params: {digitalTwinId: 'testDevice', interfaceId: 'urn:azureiot:ModelDiscovery:ModelInformation:1'},
+                    result: {isModelValid: true, modelDefinition, source: REPOSITORY_LOCATION_TYPE.Public }
+                });
             expect(reducer(deviceContentStateInitial(), action).modelDefinitionWithSource).toEqual({
                 payload: {
+                    isModelValid: true,
                     modelDefinition,
                     source: REPOSITORY_LOCATION_TYPE.Public
                 },
diff --git a/src/app/devices/deviceContent/reducer.ts b/src/app/devices/deviceContent/reducer.ts
index a71b65a22..1f168c94e 100644
--- a/src/app/devices/deviceContent/reducer.ts
+++ b/src/app/devices/deviceContent/reducer.ts
@@ -16,13 +16,13 @@ import {
     updateDeviceIdentityAction,
     patchDigitalTwinInterfacePropertiesAction,
     PatchDigitalTwinInterfacePropertiesActionParameters,
-    ModelDefinitionActionResult,
     GetModelDefinitionActionParameters
 } from './actions';
 import { Twin } from '../../api/models/device';
 import { DeviceIdentity } from '../../api/models/deviceIdentity';
 import { SynchronizationStatus } from '../../api/models/synchronizationStatus';
 import { DigitalTwinInterfaces } from '../../api/models/digitalTwinModels';
+import { ModelDefinitionWithSource } from './../../api/models/modelDefinitionWithSource';
 
 const reducer = reducerWithInitialState<DeviceContentStateType>(deviceContentStateInitial())
     //#region DeviceIdentity-related actions
@@ -129,13 +129,10 @@ const reducer = reducerWithInitialState<DeviceContentStateType>(deviceContentSta
             }
         });
     })
-    .case(getModelDefinitionAction.done, (state: DeviceContentStateType, payload: {params: GetModelDefinitionActionParameters} & {result: ModelDefinitionActionResult}) => {
+    .case(getModelDefinitionAction.done, (state: DeviceContentStateType, payload: {params: GetModelDefinitionActionParameters} & {result: ModelDefinitionWithSource}) => {
         return state.merge({
             modelDefinitionWithSource: {
-                payload: {
-                    modelDefinition: payload.result.modelDefinition,
-                    source: payload.result.source
-                },
+                payload: {...payload.result},
                 synchronizationStatus: SynchronizationStatus.fetched
             }
         });
diff --git a/src/app/devices/deviceContent/sagas/modelDefinitionSaga.spec.ts b/src/app/devices/deviceContent/sagas/modelDefinitionSaga.spec.ts
index 74842a434..251a8ef9b 100644
--- a/src/app/devices/deviceContent/sagas/modelDefinitionSaga.spec.ts
+++ b/src/app/devices/deviceContent/sagas/modelDefinitionSaga.spec.ts
@@ -5,7 +5,7 @@
 import 'jest';
 import { select, call, put } from 'redux-saga/effects';
 import { SagaIteratorClone, cloneableGenerator } from 'redux-saga/utils';
-import { getModelDefinitionSaga, getModelDefinition, getModelDefinitionFromPublicRepo, getModelDefinitionFromPrivateRepo, getModelDefinitionFromDevice, getModelDefinitionFromLocalFile } from './modelDefinitionSaga';
+import { getModelDefinitionSaga, getModelDefinition, getModelDefinitionFromPublicRepo, getModelDefinitionFromPrivateRepo, getModelDefinitionFromDevice, getModelDefinitionFromLocalFile, validateModelDefinitionHelper } from './modelDefinitionSaga';
 import * as DevicesService from '../../../api/services/devicesService';
 import { addNotificationAction } from '../../../notifications/actions';
 import { NotificationType } from '../../../api/models/notification';
@@ -30,6 +30,44 @@ describe('modelDefinitionSaga', () => {
     };
     const action = getModelDefinitionAction.started(params);
     const connectionString = 'connection_string';
+    /* tslint:disable */
+    const modelDefinition = {
+        "@id": "urn:azureiot:ModelDiscovery:DigitalTwin:1",
+        "@type": "Interface",
+        "contents": [
+            {
+                "@type": "Property",
+                "name": "modelInformation",
+                "displayName": "Model Information",
+                "description": "Providing model and optional interfaces information on a digital twin.",
+                "schema": {
+                    "@type": "Object",
+                    "fields": [
+                        {
+                            "name": "modelId",
+                            "schema": "string"
+                        },
+                        {
+                            "name": "interfaces",
+                            "schema": {
+                                "@type": "Map",
+                                "mapKey": {
+                                    "name": "name",
+                                    "schema": "string"
+                                },
+                                "mapValue": {
+                                    "name": "schema",
+                                    "schema": "string"
+                                }
+                            }
+                        }
+                    ]
+                }
+            }
+        ],
+        "@context": "http://azureiot.com/v1/contexts/Interface.json"
+    };
+    /* tslint:enable */
 
     describe('getModelDefinitionSaga', () => {
         let getModelDefinitionSagaGenerator: SagaIteratorClone;
@@ -49,16 +87,21 @@ describe('modelDefinitionSaga', () => {
             }]).value).toEqual(
                 call(getModelDefinition, action, { repositoryLocationType: REPOSITORY_LOCATION_TYPE.Public })
             );
+
+            expect(getModelDefinitionSagaGenerator.next(modelDefinition).value).toEqual(
+                call(validateModelDefinitionHelper, modelDefinition, { repositoryLocationType: REPOSITORY_LOCATION_TYPE.Public })
+            );
         });
 
         it('puts the successful action', () => {
             const success = getModelDefinitionSagaGenerator.clone();
-            expect(success.next()).toEqual({
+            expect(success.next(true)).toEqual({
                 done: false,
                 value: put((getModelDefinitionAction.done({
                     params,
                     result: {
-                        modelDefinition: undefined,
+                        isModelValid: true,
+                        modelDefinition,
                         source: REPOSITORY_LOCATION_TYPE.Public
                     }
                 })))
diff --git a/src/app/devices/deviceContent/sagas/modelDefinitionSaga.ts b/src/app/devices/deviceContent/sagas/modelDefinitionSaga.ts
index a17c50c31..dabd9ce3d 100644
--- a/src/app/devices/deviceContent/sagas/modelDefinitionSaga.ts
+++ b/src/app/devices/deviceContent/sagas/modelDefinitionSaga.ts
@@ -4,7 +4,7 @@
  **********************************************************/
 import { call, put, select } from 'redux-saga/effects';
 import { Action } from 'typescript-fsa';
-import { fetchModelDefinition } from '../../../api/services/digitalTwinsModelService';
+import { fetchModelDefinition, validateModelDefinitions } from '../../../api/services/digitalTwinsModelService';
 import { addNotificationAction } from '../../../notifications/actions';
 import { NotificationType } from '../../../api/models/notification';
 import { ResourceKeys } from '../../../../localization/resourceKeys';
@@ -22,6 +22,7 @@ import { InterfaceNotImplementedException } from './../../../shared/utils/except
 import { modelDefinitionInterfaceId, modelDefinitionCommandName } from '../../../constants/modelDefinitionConstants';
 import { FetchDigitalTwinInterfacePropertiesParameters } from '../../../api/parameters/deviceParameters';
 import { fetchLocalFile } from './../../../api/services/localRepoService';
+import { ModelDefinition } from './../../../api/models/modelDefinition';
 
 export function* getModelDefinitionSaga(action: Action<GetModelDefinitionActionParameters>) {
     try {
@@ -31,8 +32,12 @@ export function* getModelDefinitionSaga(action: Action<GetModelDefinitionActionP
         for (const location of locations) { // try to get model definition in order according to user's location settings
             try {
                 const modelDefinition = yield call (getModelDefinition, action, location);
+                const isModelValid = yield call(validateModelDefinitionHelper, modelDefinition, location);
                 yield put(getModelDefinitionAction.done(
-                    {params: action.payload, result: {modelDefinition, source: location.repositoryLocationType}}));
+                    {
+                        params: action.payload,
+                        result: {isModelValid, modelDefinition, source: location.repositoryLocationType}
+                    }));
                 break; // found the model definition, break
             }
             catch {
@@ -68,6 +73,18 @@ export function* getModelDefinitionSaga(action: Action<GetModelDefinitionActionP
     }
 }
 
+export function *validateModelDefinitionHelper(modelDefinition: ModelDefinition, location: RepositoryLocationSettings) {
+    if (location.repositoryLocationType === REPOSITORY_LOCATION_TYPE.Private || location.repositoryLocationType === REPOSITORY_LOCATION_TYPE.Public) {
+        return true;
+    }
+    try {
+        return yield call (validateModelDefinitions, JSON.stringify([modelDefinition]));
+    }
+    catch {
+        return false;
+    }
+}
+
 export function *getModelDefinitionFromPrivateRepo(action: Action<GetModelDefinitionActionParameters>, location: RepositoryLocationSettings) {
     const repoConnectionStringInfo = getRepoConnectionInfoFromConnectionString(location.value);
     const parameters: FetchModelParameters = {
diff --git a/src/app/devices/deviceList/sagas/listDeviceSaga.spec.ts b/src/app/devices/deviceList/sagas/listDeviceSaga.spec.ts
index 632a29056..f73170836 100644
--- a/src/app/devices/deviceList/sagas/listDeviceSaga.spec.ts
+++ b/src/app/devices/deviceList/sagas/listDeviceSaga.spec.ts
@@ -14,7 +14,7 @@ import { DeviceIdentity } from '../../../api/models/deviceIdentity';
 import { addNotificationAction } from '../../../notifications/actions';
 import { ResourceKeys } from '../../../../localization/resourceKeys';
 import { NotificationType } from '../../../api/models/notification';
-import { ERROR_TYPES } from '../../../api/constants';
+import { ERROR_TYPES } from '../../../constants/apiConstants';
 
 describe('listDeviceSaga', () => {
     let listDevicesSagaGenerator: SagaIteratorClone;
diff --git a/src/app/devices/deviceList/sagas/listDeviceSaga.ts b/src/app/devices/deviceList/sagas/listDeviceSaga.ts
index d2f40afa1..7d36e1e91 100644
--- a/src/app/devices/deviceList/sagas/listDeviceSaga.ts
+++ b/src/app/devices/deviceList/sagas/listDeviceSaga.ts
@@ -11,7 +11,7 @@ import { listDevicesAction } from '../actions';
 import { fetchDevices } from '../../../api/services/devicesService';
 import DeviceQuery from '../../../api/models/deviceQuery';
 import { getActiveAzureResourceConnectionStringSaga } from '../../../azureResource/sagas/getActiveAzureResourceConnectionStringSaga';
-import { ERROR_TYPES } from './../../../api/constants';
+import { ERROR_TYPES } from './../../../constants/apiConstants';
 import { appConfig } from '../../../../appConfig/appConfig';
 import { CUSTOM_CONTROLLER_PORT } from './../../../constants/browserStorage';
 
diff --git a/src/app/iotHub/sagas/getConnectionStringFromIotHubSaga.spec.ts b/src/app/iotHub/sagas/getConnectionStringFromIotHubSaga.spec.ts
index ac74636b8..aed249127 100644
--- a/src/app/iotHub/sagas/getConnectionStringFromIotHubSaga.spec.ts
+++ b/src/app/iotHub/sagas/getConnectionStringFromIotHubSaga.spec.ts
@@ -7,8 +7,8 @@ import { getConnectionStringFromIotHubSaga } from './getConnectionStringFromIotH
 import { AzureResourceIdentifier } from '../../azureResourceIdentifier/models/azureResourceIdentifier';
 import { AzureResourceIdentifierType } from '../../azureResourceIdentifier/models/azureResourceIdentifierType';
 import { getSharedAccessSignatureAuthorizationRulesSaga } from './getSharedAccessSignatureAuthorizationRulesSaga';
-import { ERROR_TYPES } from '../../api/constants';
 import { AccessRights } from '../models/accessRights';
+import { ERROR_TYPES } from '../../constants/apiConstants';
 
 describe('getConnectionStringFromIotHubSaga', () => {
     const azureResourceIdentifier: AzureResourceIdentifier = {
diff --git a/src/app/iotHub/sagas/getSharedAccessSignatureAuthorizationRulesSaga.ts b/src/app/iotHub/sagas/getSharedAccessSignatureAuthorizationRulesSaga.ts
index 1163b38b2..1afb50976 100644
--- a/src/app/iotHub/sagas/getSharedAccessSignatureAuthorizationRulesSaga.ts
+++ b/src/app/iotHub/sagas/getSharedAccessSignatureAuthorizationRulesSaga.ts
@@ -11,7 +11,7 @@ import { executeAzureResourceManagementTokenRequest } from '../../login/services
 import { appConfig } from '../../../appConfig/appConfig';
 import { StateInterface } from '../../shared/redux/state';
 import { CacheWrapper } from '../../api/models/cacheWrapper';
-import {  MILLISECONDS_PER_SECOND, SECONDS_PER_MINUTE } from '../../api/constants';
+import { SECONDS_PER_MINUTE, MILLISECONDS_PER_SECOND } from './../../constants/shared';
 
 const cacheInMinutes = 4;
 export const cacheRetentionInMilliseconds = cacheInMinutes * SECONDS_PER_MINUTE * MILLISECONDS_PER_SECOND;
diff --git a/src/app/iotHub/services/iotHubService.spec.ts b/src/app/iotHub/services/iotHubService.spec.ts
index 8f9aa0463..87314471c 100644
--- a/src/app/iotHub/services/iotHubService.spec.ts
+++ b/src/app/iotHub/services/iotHubService.spec.ts
@@ -4,8 +4,8 @@
  **********************************************************/
 import { getSharedAccessSignatureAuthorizationRules } from './iotHubService';
 import { HttpError } from '../../api/models/httpError';
-import { APPLICATION_JSON, HTTP_OPERATION_TYPES } from '../../api/constants';
 import { AccessRights } from '../models/accessRights';
+import { APPLICATION_JSON, HTTP_OPERATION_TYPES } from '../../constants/apiConstants';
 
 describe('getSharedAccessSignatureAuthorizationRules', () => {
     it('calls fetch with specified parameters', () => {
diff --git a/src/app/iotHub/services/iotHubService.ts b/src/app/iotHub/services/iotHubService.ts
index 0b7d38bfa..6418b4777 100644
--- a/src/app/iotHub/services/iotHubService.ts
+++ b/src/app/iotHub/services/iotHubService.ts
@@ -5,7 +5,7 @@
 import { SharedAccessSignatureAuthorizationRule } from '../models/sharedAccessSignatureAuthorizationRule';
 import { AzureResourceManagementEndpoint } from '../../azureResourceIdentifier/models/azureResourceManagementEndpoint';
 import { AzureResourceIdentifier } from '../../azureResourceIdentifier/models/azureResourceIdentifier';
-import { APPLICATION_JSON, HTTP_OPERATION_TYPES } from '../../api/constants';
+import { APPLICATION_JSON, HTTP_OPERATION_TYPES } from '../../constants/apiConstants';
 import { HttpError } from '../../api/models/httpError';
 
 const apiVersion = '2018-04-01';
diff --git a/src/app/settings/components/settingsPane.tsx b/src/app/settings/components/settingsPane.tsx
index 9a884ed6d..05576ae2f 100644
--- a/src/app/settings/components/settingsPane.tsx
+++ b/src/app/settings/components/settingsPane.tsx
@@ -256,8 +256,8 @@ export default class SettingsPane extends React.Component<SettingsPaneProps & Se
             isDirty: false,
             repositoryLocationSettings: [...(this.props.repositoryLocationSettings && this.props.repositoryLocationSettings.map(setting => {
                 return {
-                    connectionString: setting.value,
-                    repositoryLocationType: setting.repositoryLocationType
+                    repositoryLocationType: setting.repositoryLocationType,
+                    value: setting.value
                 };
             }))],
             showConfirmationDialog: false
diff --git a/src/app/settings/reducers.ts b/src/app/settings/reducers.ts
index 41235c3f3..71c9a3907 100644
--- a/src/app/settings/reducers.ts
+++ b/src/app/settings/reducers.ts
@@ -4,11 +4,11 @@
  **********************************************************/
 import { reducerWithInitialState } from 'typescript-fsa-reducers';
 import { setSettingsVisibilityAction, setSettingsRepositoryLocationsAction, updateRepoTokenAction } from './actions';
-import { applicationStateInitial, ApplicationStateType, OFFSET_IN_MINUTES, PrivateRepositorySettings, RepositoryLocationSettings } from './state';
+import { applicationStateInitial, ApplicationStateType, PrivateRepositorySettings, RepositoryLocationSettings } from './state';
 import { REPO_LOCATIONS } from '../constants/browserStorage';
 import { REPOSITORY_LOCATION_TYPE } from './../constants/repositoryLocationTypes';
 import { PRIVATE_REPO_CONNECTION_STRING_NAME, LOCAL_FILE_EXPLORER_PATH_NAME } from './../constants/browserStorage';
-import { MILLISECONDS_IN_MINUTE } from '../constants/shared';
+import { MILLISECONDS_IN_MINUTE, OFFSET_IN_MINUTES } from '../constants/shared';
 
 const reducer = reducerWithInitialState<ApplicationStateType>(applicationStateInitial())
     .case(setSettingsVisibilityAction, (state: ApplicationStateType, payload: boolean) => {
diff --git a/src/app/settings/state.ts b/src/app/settings/state.ts
index e3bad273d..488a5ee6c 100644
--- a/src/app/settings/state.ts
+++ b/src/app/settings/state.ts
@@ -6,9 +6,9 @@ import { Record } from 'immutable';
 import { IM } from '../shared/types/types';
 import { REPOSITORY_LOCATION_TYPE } from '../constants/repositoryLocationTypes';
 import { PRIVATE_REPO_CONNECTION_STRING_NAME, REPO_LOCATIONS, LOCAL_FILE_EXPLORER_PATH_NAME } from '../constants/browserStorage';
-import { MILLISECONDS_IN_MINUTE, PUBLIC_REPO_HOSTNAME } from '../constants/shared';
+import { MILLISECONDS_IN_MINUTE, OFFSET_IN_MINUTES } from '../constants/shared';
 import { appConfig, HostMode } from '../../appConfig/appConfig';
-export const OFFSET_IN_MINUTES = 15;
+import { PUBLIC_REPO_HOSTNAME } from '../constants/apiConstants';
 
 export interface RepositoryLocationSettings {
     repositoryLocationType: REPOSITORY_LOCATION_TYPE;
diff --git a/src/localization/locales/en.json b/src/localization/locales/en.json
index abc8ddaa4..7c458713c 100644
--- a/src/localization/locales/en.json
+++ b/src/localization/locales/en.json
@@ -70,7 +70,7 @@
                     "label":"Company repository",
                     "infoText": "",
                     "textBoxLabel": "Company model repository connection string",
-                    "placeholder": "Please fill in this required field in order to proceed"
+                    "placeholder": ""
                 },
                 "device": {
                     "label":"On the connected device",
@@ -79,9 +79,9 @@
                 "local": {
                     "labelInElectron":"Local folder",
                     "labelInBrowser":"Local folder (This is only enabled in the desktop version from: https://github.com/Azure/azure-iot-explorer/releases)",
-                    "infoText": "Use your local folder as a model repository. The files in the folder should be named the same as the Interface ID with all ':' removed, and should be in the format of json. For example: urn:contoso:com:EnvironmentalSensor:1 should be named as urncontosocomEnvironmentalSensor1.json",
+                    "infoText": "Use your local folder as a model repository. The interface files you wish to use should have a json extension and a file name equal to the Interface ID with all colons (':') removed. For example: urn:contoso:com:EnvironmentalSensor:1 should be named as urncontosocomEnvironmentalSensor1.json",
                     "textBoxLabel": "Local folder path",
-                    "placeholder": "Please fill in this required field in order to proceed. For example: f:/"
+                    "placeholder": "f:/"
                 }
             }
         },
@@ -476,7 +476,8 @@
         },
         "headerText": "Interface",
         "noInterfaces": "No interfaces",
-        "interfaceNotFound": "We are not able to retrieve interface model definition. Please click 'Configure' button below to see how we resolve model definition."
+        "interfaceNotFound": "We are not able to retrieve interface model definition. Please click 'Configure' button below to see how we resolve model definition.",
+        "interfaceNotValid": "Model definition is not valid. Please update the model definition and then proceed."
     },
     "deviceEvents": {
         "command" : {
diff --git a/src/localization/resourceKeys.ts b/src/localization/resourceKeys.ts
index 5de5b4d5f..2561e010b 100644
--- a/src/localization/resourceKeys.ts
+++ b/src/localization/resourceKeys.ts
@@ -336,6 +336,7 @@ export class ResourceKeys {
       },
       headerText : "deviceInterfaces.headerText",
       interfaceNotFound : "deviceInterfaces.interfaceNotFound",
+      interfaceNotValid : "deviceInterfaces.interfaceNotValid",
       noInterfaces : "deviceInterfaces.noInterfaces",
    };
    public static deviceLists = {