diff --git a/packages/openactive-broker-microservice/package-lock.json b/packages/openactive-broker-microservice/package-lock.json
index d3552eb4fd..4fce6935f1 100644
--- a/packages/openactive-broker-microservice/package-lock.json
+++ b/packages/openactive-broker-microservice/package-lock.json
@@ -159,9 +159,9 @@
       }
     },
     "@openactive/data-models": {
-      "version": "2.0.262",
-      "resolved": "https://registry.npmjs.org/@openactive/data-models/-/data-models-2.0.262.tgz",
-      "integrity": "sha512-EbSjwhHDgkEWNvftCV8jFWI1YrLLvU4+klshQgY6OpYbzxYDHkkjZb73tM7Ij6M8qnzOc/k9FJoj87c86l4GYg=="
+      "version": "2.0.271",
+      "resolved": "https://registry.npmjs.org/@openactive/data-models/-/data-models-2.0.271.tgz",
+      "integrity": "sha512-hjrVPzftlelX4+nCJpWzkZJLyXETuv/dTDGRA0HSjXIKPti6zSdJho+NWvY5OiNYREQ+RgDuwzPK0ZSoL0cDuw=="
     },
     "@openactive/openactive-openid-test-client": {
       "version": "file:../openactive-openid-test-client",
diff --git a/packages/openactive-broker-microservice/package.json b/packages/openactive-broker-microservice/package.json
index 5181cdce24..8a396b780f 100644
--- a/packages/openactive-broker-microservice/package.json
+++ b/packages/openactive-broker-microservice/package.json
@@ -15,7 +15,7 @@
   "license": "MIT",
   "dependencies": {
     "@openactive/data-model-validator": "^2.0.52",
-    "@openactive/data-models": "^2.0.262",
+    "@openactive/data-models": "^2.0.271",
     "@openactive/openactive-openid-test-client": "file:../openactive-openid-test-client",
     "@openactive/rpde-validator": "^2.0.9",
     "@openactive/test-interface-criteria": "file:../test-interface-criteria",
diff --git a/packages/openactive-integration-tests/package-lock.json b/packages/openactive-integration-tests/package-lock.json
index 3cb9263fff..5e901a3463 100644
--- a/packages/openactive-integration-tests/package-lock.json
+++ b/packages/openactive-integration-tests/package-lock.json
@@ -942,9 +942,9 @@
       }
     },
     "@openactive/data-models": {
-      "version": "2.0.262",
-      "resolved": "https://registry.npmjs.org/@openactive/data-models/-/data-models-2.0.262.tgz",
-      "integrity": "sha512-EbSjwhHDgkEWNvftCV8jFWI1YrLLvU4+klshQgY6OpYbzxYDHkkjZb73tM7Ij6M8qnzOc/k9FJoj87c86l4GYg=="
+      "version": "2.0.271",
+      "resolved": "https://registry.npmjs.org/@openactive/data-models/-/data-models-2.0.271.tgz",
+      "integrity": "sha512-hjrVPzftlelX4+nCJpWzkZJLyXETuv/dTDGRA0HSjXIKPti6zSdJho+NWvY5OiNYREQ+RgDuwzPK0ZSoL0cDuw=="
     },
     "@openactive/openactive-openid-test-client": {
       "version": "file:../openactive-openid-test-client",
diff --git a/packages/openactive-integration-tests/package.json b/packages/openactive-integration-tests/package.json
index 4d6998b153..fa67f5a123 100644
--- a/packages/openactive-integration-tests/package.json
+++ b/packages/openactive-integration-tests/package.json
@@ -18,7 +18,7 @@
   "eslintConfig": {},
   "dependencies": {
     "@openactive/data-model-validator": "^2.0.52",
-    "@openactive/data-models": "^2.0.262",
+    "@openactive/data-models": "^2.0.271",
     "@openactive/openactive-openid-test-client": "file:../openactive-openid-test-client",
     "@openactive/test-interface-criteria": "file:../test-interface-criteria",
     "async-mutex": "^0.3.1",
diff --git a/packages/openactive-integration-tests/test/features/core/common-error-conditions/README.md b/packages/openactive-integration-tests/test/features/core/common-error-conditions/README.md
index 4005877727..3409164d67 100644
--- a/packages/openactive-integration-tests/test/features/core/common-error-conditions/README.md
+++ b/packages/openactive-integration-tests/test/features/core/common-error-conditions/README.md
@@ -39,7 +39,7 @@ This feature is **required** by the Open Booking API specification, and so must
 | [incomplete-customer-details](./implemented/incomplete-customer-details-test.js) | Expect an IncompleteCustomerDetailsError when customer details are missing the required email property | Run each of C2 and B for a valid opportunity, with customer details missing the required email property, expecting an IncompleteCustomerDetailsError to be returned (C1 is ignored because customer details are not accepted for C1) | [TestOpportunityBookable](https://openactive.io/test-interface#TestOpportunityBookable) x8 |
 | [incomplete-order-item-no-offer](./implemented/incomplete-order-item-no-offer-test.js) | Test for IncompleteOrderItemError with missing `acceptedOffer` | Test for IncompleteOrderItemError (at C1, C2 and B). If there is a missing `acceptedOffer` property on the OrderItem. | [TestOpportunityBookable](https://openactive.io/test-interface#TestOpportunityBookable) x4 |
 | [incomplete-order-item-no-opportunity](./implemented/incomplete-order-item-no-opportunity-test.js) | Test for IncompleteOrderItemError with missing `orderedItem` | Test for IncompleteOrderItemError (at C1, C2 and B). If there is a missing `orderedItem` property on the OrderItem. | [TestOpportunityBookable](https://openactive.io/test-interface#TestOpportunityBookable) x4 |
-| [opportunity-in-past](./implemented/opportunity-in-past-test.js) | Expect an OpportunityOfferPairNotBookableError when opportunity is in the past | Runs C1, C2 and B for an opportunity in the past, expecting an OpportunityOfferPairNotBookableError to be returned at C1 and C2, and an UnableToProcessOrderItemError to be returned at B | [TestOpportunityBookableInPast](https://openactive.io/test-interface#TestOpportunityBookableInPast) x3, [TestOpportunityBookable](https://openactive.io/test-interface#TestOpportunityBookable) x1 |
+| [opportunity-in-past](./implemented/opportunity-in-past-test.js) | Expect an OpportunityOfferPairNotBookableError when opportunity is in the past | Runs C1, C2 and B for an opportunity in the past, expecting an OpportunityOfferPairNotBookableError to be returned at C1, C2, and B | [TestOpportunityBookableInPast](https://openactive.io/test-interface#TestOpportunityBookableInPast) x3, [TestOpportunityBookable](https://openactive.io/test-interface#TestOpportunityBookable) x1 |
 | [unknown-endpoint](./implemented/unknown-endpoint-test.js) | Expect an UnknownOrIncorrectEndpointError for requests to unknown endpoints | Send a request to an endpoint that does not exist, and expect an UnknownOrIncorrectEndpointError to be returned |  |
 
 
diff --git a/packages/openactive-integration-tests/test/features/core/common-error-conditions/implemented/incomplete-order-item-no-offer-test.js b/packages/openactive-integration-tests/test/features/core/common-error-conditions/implemented/incomplete-order-item-no-offer-test.js
index f63c45fe9f..eae6ab4e97 100644
--- a/packages/openactive-integration-tests/test/features/core/common-error-conditions/implemented/incomplete-order-item-no-offer-test.js
+++ b/packages/openactive-integration-tests/test/features/core/common-error-conditions/implemented/incomplete-order-item-no-offer-test.js
@@ -3,7 +3,7 @@ const {
   FlowStageUtils,
   FlowStageRecipes,
 } = require('../../../../helpers/flow-stages');
-const { itShouldIncludeErrorForOnlyPrimaryOrderItems, itShouldReturnAnOpenBookingError } = require('../../../../shared-behaviours/errors');
+const { itShouldIncludeErrorForOnlyPrimaryOrderItems } = require('../../../../shared-behaviours/errors');
 
 /**
  * @typedef {import('../../../../helpers/flow-stages/c1').C1FlowStageType} C1FlowStageType
@@ -48,7 +48,7 @@ FeatureHelper.describeFeature(module, {
   FlowStageUtils.describeRunAndRunChecks({ doCheckIsValid: false, doCheckSuccess: false }, c2, () => {
     itShouldIncludeIncompleteOrderItemErrorWhereRelevant(c2);
   });
-  FlowStageUtils.describeRunAndCheckIsValid(bookRecipe.firstStage, () => {
-    itShouldReturnAnOpenBookingError('UnableToProcessOrderItemError', 409, () => bookRecipe.firstStage.getOutput().httpResponse);
+  FlowStageUtils.describeRunAndRunChecks({ doCheckIsValid: false, doCheckSuccess: false }, bookRecipe.firstStage, () => {
+    itShouldIncludeIncompleteOrderItemErrorWhereRelevant(bookRecipe.firstStage);
   });
 });
diff --git a/packages/openactive-integration-tests/test/features/core/common-error-conditions/implemented/incomplete-order-item-no-opportunity-test.js b/packages/openactive-integration-tests/test/features/core/common-error-conditions/implemented/incomplete-order-item-no-opportunity-test.js
index 15473cd841..45e6ec298f 100644
--- a/packages/openactive-integration-tests/test/features/core/common-error-conditions/implemented/incomplete-order-item-no-opportunity-test.js
+++ b/packages/openactive-integration-tests/test/features/core/common-error-conditions/implemented/incomplete-order-item-no-opportunity-test.js
@@ -3,7 +3,7 @@ const {
   FlowStageUtils,
   FlowStageRecipes,
 } = require('../../../../helpers/flow-stages');
-const { itShouldIncludeErrorForOnlyPrimaryOrderItems, itShouldReturnAnOpenBookingError } = require('../../../../shared-behaviours/errors');
+const { itShouldIncludeErrorForOnlyPrimaryOrderItems } = require('../../../../shared-behaviours/errors');
 
 /**
  * @typedef {import('../../../../helpers/flow-stages/c1').C1FlowStageType} C1FlowStageType
@@ -48,7 +48,7 @@ FeatureHelper.describeFeature(module, {
   FlowStageUtils.describeRunAndRunChecks({ doCheckIsValid: false, doCheckSuccess: false }, c2, () => {
     itShouldIncludeIncompleteOrderItemErrorWhereRelevant(c2);
   });
-  FlowStageUtils.describeRunAndCheckIsValid(bookRecipe.firstStage, () => {
-    itShouldReturnAnOpenBookingError('UnableToProcessOrderItemError', 409, () => bookRecipe.firstStage.getOutput().httpResponse);
+  FlowStageUtils.describeRunAndRunChecks({ doCheckIsValid: false, doCheckSuccess: false }, bookRecipe.firstStage, () => {
+    itShouldIncludeIncompleteOrderItemErrorWhereRelevant(bookRecipe.firstStage);
   });
 });
diff --git a/packages/openactive-integration-tests/test/features/core/common-error-conditions/implemented/opportunity-in-past-test.js b/packages/openactive-integration-tests/test/features/core/common-error-conditions/implemented/opportunity-in-past-test.js
index d18a3b774a..482057cb43 100644
--- a/packages/openactive-integration-tests/test/features/core/common-error-conditions/implemented/opportunity-in-past-test.js
+++ b/packages/openactive-integration-tests/test/features/core/common-error-conditions/implemented/opportunity-in-past-test.js
@@ -1,6 +1,6 @@
 const { FeatureHelper } = require('../../../../helpers/feature-helper');
 const { FlowStageRecipes, FlowStageUtils } = require('../../../../helpers/flow-stages');
-const { itShouldIncludeErrorForOnlyPrimaryOrderItems, itShouldReturnAnOpenBookingError } = require('../../../../shared-behaviours/errors');
+const { itShouldIncludeErrorForOnlyPrimaryOrderItems } = require('../../../../shared-behaviours/errors');
 
 /**
  * @typedef {import('../../../../helpers/flow-stages/c1').C1FlowStageType} C1FlowStageType
@@ -13,7 +13,7 @@ FeatureHelper.describeFeature(module, {
   testFeatureImplemented: true,
   testIdentifier: 'opportunity-in-past',
   testName: 'Expect an OpportunityOfferPairNotBookableError when opportunity is in the past',
-  testDescription: 'Runs C1, C2 and B for an opportunity in the past, expecting an OpportunityOfferPairNotBookableError to be returned at C1 and C2, and an UnableToProcessOrderItemError to be returned at B',
+  testDescription: 'Runs C1, C2 and B for an opportunity in the past, expecting an OpportunityOfferPairNotBookableError to be returned at C1, C2, and B',
   // The primary opportunity criteria to use for the primary OrderItem under test
   testOpportunityCriteria: 'TestOpportunityBookableInPast',
   // The secondary opportunity criteria to use for multiple OrderItem tests
@@ -43,6 +43,6 @@ FeatureHelper.describeFeature(module, {
     itShouldIncludeOpportunityOfferPairNotBookableErrorWhereRelevant(c2);
   });
   FlowStageUtils.describeRunAndCheckIsValid(bookRecipe.firstStage, () => {
-    itShouldReturnAnOpenBookingError('UnableToProcessOrderItemError', 409, () => bookRecipe.firstStage.getOutput().httpResponse);
+    itShouldIncludeOpportunityOfferPairNotBookableErrorWhereRelevant(bookRecipe.firstStage);
   });
 });
diff --git a/packages/openactive-integration-tests/test/features/details-capture/additional-details-capture/implemented/additional-details-required-but-not-supplied-test.js b/packages/openactive-integration-tests/test/features/details-capture/additional-details-capture/implemented/additional-details-required-but-not-supplied-test.js
index 06737cc689..1d0e793064 100644
--- a/packages/openactive-integration-tests/test/features/details-capture/additional-details-capture/implemented/additional-details-required-but-not-supplied-test.js
+++ b/packages/openactive-integration-tests/test/features/details-capture/additional-details-capture/implemented/additional-details-required-but-not-supplied-test.js
@@ -1,7 +1,6 @@
 const chai = require('chai');
 const { FeatureHelper } = require('../../../../helpers/feature-helper');
 const { FlowStageRecipes, FlowStageUtils } = require('../../../../helpers/flow-stages');
-const { itShouldReturnAnOpenBookingError } = require('../../../../shared-behaviours/errors');
 
 FeatureHelper.describeFeature(module, {
   testCategory: 'details-capture',
@@ -21,10 +20,10 @@ FeatureHelper.describeFeature(module, {
   FlowStageUtils.describeRunAndCheckIsSuccessfulAndValid(fetchOpportunities);
   FlowStageUtils.describeRunAndCheckIsSuccessfulAndValid(c1);
 
-  FlowStageUtils.describeRunAndCheckIsValid(c2, () => {
+  function itShouldReturnAnIncompleteIntakeFormError(flowStage) {
     it('should return an IncompleteIntakeFormError on the OrderItem', () => {
       const positionsOfOrderItemsThatNeedIntakeForms = Object.keys(c1.getOutput().positionOrderIntakeFormMap).map(parseInt);
-      const orderItemsThatNeedIntakeForms = c2.getOutput().httpResponse.body.orderedItem
+      const orderItemsThatNeedIntakeForms = flowStage.getOutput().httpResponse.body.orderedItem
         .filter(orderItem => positionsOfOrderItemsThatNeedIntakeForms.includes(orderItem.position));
 
       for (const orderItem of orderItemsThatNeedIntakeForms) {
@@ -34,8 +33,13 @@ FeatureHelper.describeFeature(module, {
         chai.expect(incompleteIntakeFormErrors).to.have.lengthOf.above(0);
       }
     });
+  }
+
+  FlowStageUtils.describeRunAndCheckIsValid(c2, () => {
+    itShouldReturnAnIncompleteIntakeFormError(c2);
   });
+
   FlowStageUtils.describeRunAndCheckIsValid(bookRecipe.firstStage, () => {
-    itShouldReturnAnOpenBookingError('UnableToProcessOrderItemError', 409, () => bookRecipe.firstStage.getOutput().httpResponse);
+    itShouldReturnAnIncompleteIntakeFormError(bookRecipe.firstStage);
   });
 });
diff --git a/packages/openactive-integration-tests/test/features/details-capture/additional-details-capture/implemented/additional-details-required-invalid-details-supplied-test.js b/packages/openactive-integration-tests/test/features/details-capture/additional-details-capture/implemented/additional-details-required-invalid-details-supplied-test.js
index da4d55f4bf..467c29ed4a 100644
--- a/packages/openactive-integration-tests/test/features/details-capture/additional-details-capture/implemented/additional-details-required-invalid-details-supplied-test.js
+++ b/packages/openactive-integration-tests/test/features/details-capture/additional-details-capture/implemented/additional-details-required-invalid-details-supplied-test.js
@@ -1,7 +1,6 @@
 const chai = require('chai');
 const { FeatureHelper } = require('../../../../helpers/feature-helper');
 const { FlowStageRecipes, FlowStageUtils } = require('../../../../helpers/flow-stages');
-const { itShouldReturnAnOpenBookingError } = require('../../../../shared-behaviours/errors');
 
 FeatureHelper.describeFeature(module, {
   testCategory: 'details-capture',
@@ -22,10 +21,10 @@ FeatureHelper.describeFeature(module, {
   FlowStageUtils.describeRunAndCheckIsSuccessfulAndValid(fetchOpportunities);
   FlowStageUtils.describeRunAndCheckIsSuccessfulAndValid(c1);
 
-  FlowStageUtils.describeRunAndCheckIsValid(c2, () => {
-    it('should return an IncompleteAttendeeDetailsError on the OrderItem', () => {
+  function itShouldReturnAnInvalidIntakeFormError(flowStage) {
+    it('should return an InvalidIntakeFormError on the OrderItem', () => {
       const positionsOfOrderItemsThatNeedIntakeForms = Object.keys(c1.getOutput().positionOrderIntakeFormMap).map(parseInt);
-      const orderItemsThatNeedIntakeForms = c2.getOutput().httpResponse.body.orderedItem
+      const orderItemsThatNeedIntakeForms = flowStage.getOutput().httpResponse.body.orderedItem
         .filter(orderItem => positionsOfOrderItemsThatNeedIntakeForms.includes(orderItem.position));
 
       for (const orderItem of orderItemsThatNeedIntakeForms) {
@@ -35,8 +34,12 @@ FeatureHelper.describeFeature(module, {
         chai.expect(incompleteIntakeFormErrors).to.have.lengthOf.above(0);
       }
     });
+  }
+
+  FlowStageUtils.describeRunAndCheckIsValid(c2, () => {
+    itShouldReturnAnInvalidIntakeFormError(c2);
   });
   FlowStageUtils.describeRunAndCheckIsValid(bookRecipe.firstStage, () => {
-    itShouldReturnAnOpenBookingError('UnableToProcessOrderItemError', 409, () => bookRecipe.firstStage.getOutput().httpResponse);
+    itShouldReturnAnInvalidIntakeFormError(bookRecipe.firstStage);
   });
 });
diff --git a/packages/openactive-integration-tests/test/features/details-capture/attendee-details-capture/implemented/attendee-details-not-included-test.js b/packages/openactive-integration-tests/test/features/details-capture/attendee-details-capture/implemented/attendee-details-not-included-test.js
index e41ca54305..38f1e53162 100644
--- a/packages/openactive-integration-tests/test/features/details-capture/attendee-details-capture/implemented/attendee-details-not-included-test.js
+++ b/packages/openactive-integration-tests/test/features/details-capture/attendee-details-capture/implemented/attendee-details-not-included-test.js
@@ -2,7 +2,6 @@ const _ = require('lodash');
 const chai = require('chai');
 const { FeatureHelper } = require('../../../../helpers/feature-helper');
 const { FlowStageRecipes, FlowStageUtils } = require('../../../../helpers/flow-stages');
-const { itShouldReturnAnOpenBookingError } = require('../../../../shared-behaviours/errors');
 
 FeatureHelper.describeFeature(module, {
   testCategory: 'details-capture',
@@ -22,12 +21,12 @@ FeatureHelper.describeFeature(module, {
   FlowStageUtils.describeRunAndCheckIsSuccessfulAndValid(fetchOpportunities);
   FlowStageUtils.describeRunAndCheckIsSuccessfulAndValid(c1);
 
-  FlowStageUtils.describeRunAndCheckIsValid(c2, () => {
+  function itShouldReturnAnIncompleteAttendeeDetailsError(flowStage) {
     it('should return an IncompleteAttendeeDetailsError on the OrderItem', () => {
       const positionsOfOrderItemsThatNeedAttendeeDetails = c1.getOutput().httpResponse.body.orderedItem
         .filter(orderItem => !_.isNil(orderItem.attendeeDetailsRequired))
         .map(orderItem => orderItem.position);
-      const orderItemsThatNeedAttendeeDetails = c2.getOutput().httpResponse.body.orderedItem
+      const orderItemsThatNeedAttendeeDetails = flowStage.getOutput().httpResponse.body.orderedItem
         .filter(orderItem => positionsOfOrderItemsThatNeedAttendeeDetails.includes(orderItem.position));
 
       for (const orderItem of orderItemsThatNeedAttendeeDetails) {
@@ -37,8 +36,13 @@ FeatureHelper.describeFeature(module, {
         chai.expect(incompleteIntakeFormErrors).to.have.lengthOf.above(0);
       }
     });
+  }
+
+  FlowStageUtils.describeRunAndCheckIsValid(c2, () => {
+    itShouldReturnAnIncompleteAttendeeDetailsError(c2);
   });
+
   FlowStageUtils.describeRunAndCheckIsValid(bookRecipe.firstStage, () => {
-    itShouldReturnAnOpenBookingError('UnableToProcessOrderItemError', 409, () => bookRecipe.firstStage.getOutput().httpResponse);
+    itShouldReturnAnIncompleteAttendeeDetailsError(bookRecipe.firstStage);
   });
 });
diff --git a/packages/openactive-integration-tests/test/features/payment/prepayment-required-unavailable/implemented/prepayment-required-unavailable-conflict-error-test.js b/packages/openactive-integration-tests/test/features/payment/prepayment-required-unavailable/implemented/prepayment-required-unavailable-conflict-error-test.js
index c923a73beb..b5f72929b8 100644
--- a/packages/openactive-integration-tests/test/features/payment/prepayment-required-unavailable/implemented/prepayment-required-unavailable-conflict-error-test.js
+++ b/packages/openactive-integration-tests/test/features/payment/prepayment-required-unavailable/implemented/prepayment-required-unavailable-conflict-error-test.js
@@ -1,6 +1,6 @@
 const { FeatureHelper } = require('../../../../helpers/feature-helper');
 const { FlowStageRecipes, FlowStageUtils } = require('../../../../helpers/flow-stages');
-const { itShouldReturnAnOpenBookingError, itShouldIncludeErrorForOnlyPrimaryOrderItems } = require('../../../../shared-behaviours/errors');
+const { itShouldIncludeErrorForOnlyPrimaryOrderItems } = require('../../../../shared-behaviours/errors');
 
 /**
  * @typedef {import('../../../../helpers/flow-stages/c1').C1FlowStageType} C1FlowStageType
@@ -70,6 +70,6 @@ FeatureHelper.describeFeature(module, {
     itShouldIncludeOpportunityIsInConflictErrorWhereRelevant(c2);
   });
   FlowStageUtils.describeRunAndCheckIsValid(bookRecipe.firstStage, () => {
-    itShouldReturnAnOpenBookingError('UnableToProcessOrderItemError', 409, () => bookRecipe.firstStage.getOutput().httpResponse);
+    itShouldIncludeOpportunityIsInConflictErrorWhereRelevant(bookRecipe.firstStage);
   });
 });
diff --git a/packages/openactive-integration-tests/test/shared-behaviours/validation.js b/packages/openactive-integration-tests/test/shared-behaviours/validation.js
index 244b644107..d408578504 100644
--- a/packages/openactive-integration-tests/test/shared-behaviours/validation.js
+++ b/packages/openactive-integration-tests/test/shared-behaviours/validation.js
@@ -99,9 +99,14 @@ function shouldBeValidResponse(getter, name, logger, options, opportunityCriteri
     const statusCode = response.response && response.response.statusCode;
     const statusMessage = response.response && response.response.statusMessage;
 
-    // Note C1Response and C2Response are permitted to return 409 errors of type `OrderQuote`, instead of `OpenBookingError`
-    if ((statusCode < 200 || statusCode >= 300) && !(statusCode === 409 && (options.validationMode === 'C1Response' || options.validationMode === 'C2Response'))) {
-      optionsWithRemoteJson.validationMode = 'OpenBookingError';
+    // Note C1Response, C2Response, BResponse and PResponse are permitted to return 409 errors of type `OrderQuote`, `OrderProposal`, or `Order` instead of `OpenBookingError`
+    if (statusCode < 200 || statusCode >= 300) {
+      // TODO: Test suite should assert whether the response is expected to be an OrderItemError, instead of basing validation on the response status code
+      if (statusCode === 409 && (options.validationMode === 'C1Response' || options.validationMode === 'C2Response' || options.validationMode === 'BResponse' || options.validationMode === 'PResponse')) {
+        optionsWithRemoteJson.validationMode = `${options.validationMode}OrderItemError`;
+      } else {
+        optionsWithRemoteJson.validationMode = 'OpenBookingError';
+      }
 
       // little nicer error message for completely failed responses.
       if (!body) {