diff --git a/src/evaluator/index.ts b/src/evaluator/index.ts
index 70dad68a..62f82e98 100644
--- a/src/evaluator/index.ts
+++ b/src/evaluator/index.ts
@@ -94,7 +94,7 @@ export function evaluateFeaturesByFlagSets(
   flagSets: string[],
   attributes: SplitIO.Attributes | undefined,
   storage: IStorageSync | IStorageAsync,
-): MaybeThenable<Record<string,IEvaluationResult>> {
+): MaybeThenable<Record<string, IEvaluationResult>> {
   let storedFlagNames: MaybeThenable<ISet<string>>;
 
   // get features by flag sets
@@ -107,7 +107,10 @@ export function evaluateFeaturesByFlagSets(
 
   // evaluate related features
   return thenable(storedFlagNames) ?
-    storedFlagNames.then((splitNames) => evaluateFeatures(log, key, setToArray(splitNames), attributes, storage)) :
+    storedFlagNames.then((splitNames) => evaluateFeatures(log, key, setToArray(splitNames), attributes, storage))
+      .catch(() => {
+        return {};
+      }) :
     evaluateFeatures(log, key, setToArray(storedFlagNames), attributes, storage);
 }
 
diff --git a/src/storages/inRedis/SplitsCacheInRedis.ts b/src/storages/inRedis/SplitsCacheInRedis.ts
index 310c014d..f58f49ab 100644
--- a/src/storages/inRedis/SplitsCacheInRedis.ts
+++ b/src/storages/inRedis/SplitsCacheInRedis.ts
@@ -5,7 +5,7 @@ import { ILogger } from '../../logger/types';
 import { LOG_PREFIX } from './constants';
 import { ISplit } from '../../dtos/types';
 import { AbstractSplitsCacheAsync } from '../AbstractSplitsCacheAsync';
-import { ISet, _Set } from '../../utils/lang/sets';
+import { ISet } from '../../utils/lang/sets';
 
 /**
  * Discard errors for an answer of multiple operations.
@@ -196,8 +196,8 @@ export class SplitsCacheInRedis extends AbstractSplitsCacheAsync {
    * @todo this is a no-op method to be implemented
   */
   getNamesByFlagSets(): Promise<ISet<string>> {
-    // eslint-disable-next-line @typescript-eslint/no-unused-vars
-    return new Promise(flagSets => new _Set([]));
+    this.log.error(LOG_PREFIX + 'ByFlagSet/s evaluations are not supported with Redis storage yet.');
+    return Promise.reject();
   }
 
   /**
diff --git a/src/storages/pluggable/SplitsCachePluggable.ts b/src/storages/pluggable/SplitsCachePluggable.ts
index c6dce829..786fb8a5 100644
--- a/src/storages/pluggable/SplitsCachePluggable.ts
+++ b/src/storages/pluggable/SplitsCachePluggable.ts
@@ -5,7 +5,7 @@ import { ILogger } from '../../logger/types';
 import { ISplit } from '../../dtos/types';
 import { LOG_PREFIX } from './constants';
 import { AbstractSplitsCacheAsync } from '../AbstractSplitsCacheAsync';
-import { ISet, _Set } from '../../utils/lang/sets';
+import { ISet } from '../../utils/lang/sets';
 
 /**
  * ISplitsCacheAsync implementation for pluggable storages.
@@ -162,8 +162,8 @@ export class SplitsCachePluggable extends AbstractSplitsCacheAsync {
    * @todo this is a no-op method to be implemented
   */
   getNamesByFlagSets(): Promise<ISet<string>> {
-    // eslint-disable-next-line @typescript-eslint/no-unused-vars
-    return new Promise(flagSets => new _Set([]));
+    this.log.error(LOG_PREFIX + 'ByFlagSet/s evaluations are not supported with pluggable storage yet.');
+    return Promise.reject();
   }
 
   /**