diff --git a/CHANGELOG.md b/CHANGELOG.md
index 451051777d..b769b51a6d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,15 @@
 
 All notable changes to this project will be documented in this file. See [standard-version](https://github.com/conventional-changelog/standard-version) for commit guidelines.
 
+### [1.51.1](https://github.com/rudderlabs/rudder-transformer/compare/v1.51.0...v1.51.1) (2023-12-06)
+
+
+### Bug Fixes
+
+* marketo backward compatibility ([#2880](https://github.com/rudderlabs/rudder-transformer/issues/2880)) ([af6aebb](https://github.com/rudderlabs/rudder-transformer/commit/af6aebba9a9891fadc91fe2dc4ae4db4b1e269c9))
+* marketo new field introduction backward compatibility ([cd6c3b0](https://github.com/rudderlabs/rudder-transformer/commit/cd6c3b0672a0b17078627f28f6613a2ef1898ee7))
+* remove ErrorResponse type from postTransfomration delivery ([b13f0a6](https://github.com/rudderlabs/rudder-transformer/commit/b13f0a6340177a56417692ad7dcf3829d4990826))
+
 ## [1.51.0](https://github.com/rudderlabs/rudder-transformer/compare/v1.50.1...v1.51.0) (2023-12-06)
 
 
diff --git a/package-lock.json b/package-lock.json
index 24e6a3bc3a..27655f81ef 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "rudder-transformer",
-  "version": "1.51.0",
+  "version": "1.51.1",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "rudder-transformer",
-      "version": "1.51.0",
+      "version": "1.51.1",
       "license": "ISC",
       "dependencies": {
         "@amplitude/ua-parser-js": "^0.7.24",
diff --git a/package.json b/package.json
index 457c0eecf2..a36ac26e9c 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "rudder-transformer",
-  "version": "1.51.0",
+  "version": "1.51.1",
   "description": "",
   "homepage": "https://github.com/rudderlabs/rudder-transformer#readme",
   "bugs": {
diff --git a/src/cdk/v2/destinations/tiktok_audience/rtWorkflow.yaml b/src/cdk/v2/destinations/tiktok_audience/rtWorkflow.yaml
index 3db4c405ad..a7fa855938 100644
--- a/src/cdk/v2/destinations/tiktok_audience/rtWorkflow.yaml
+++ b/src/cdk/v2/destinations/tiktok_audience/rtWorkflow.yaml
@@ -13,7 +13,6 @@ steps:
     loopOverInput: true
 
   - name: successfulEvents
-    debug: true
     template: |
       $.outputs.transform#idx{"output" in .}.({
           "batchedRequest": .output,
diff --git a/src/services/destination/postTransformation.ts b/src/services/destination/postTransformation.ts
index 1e99961045..0b91eb7cc1 100644
--- a/src/services/destination/postTransformation.ts
+++ b/src/services/destination/postTransformation.ts
@@ -16,15 +16,6 @@ import { ErrorReportingService } from '../errorReporting';
 import tags from '../../v0/util/tags';
 import stats from '../../util/stats';
 
-type ErrorResponse = {
-  status?: number;
-  message?: string;
-  destinationResponse?: object;
-  statTags?: object;
-  authErrorCategory?: string | undefined;
-  response?: object | undefined;
-};
-
 export class DestinationPostTransformationService {
   public static handleProcessorTransformSucessEvents(
     event: ProcessorTransformationRequest,
@@ -148,7 +139,7 @@ export class DestinationPostTransformationService {
   }
 
   public static handleDeliveryFailureEvents(
-    error: ErrorResponse,
+    error: NonNullable<unknown>,
     metaTo: MetaTransferObject,
   ): DeliveryResponse {
     const errObj = generateErrorObject(error, metaTo.errorDetails, false);
@@ -161,12 +152,6 @@ export class DestinationPostTransformationService {
         authErrorCategory: errObj.authErrorCategory,
       }),
     } as DeliveryResponse;
-
-    // for transformer-proxy to maintain contract
-    const { response } = error;
-    if (response) {
-      resp.response = response;
-    }
     ErrorReportingService.reportError(error, metaTo.errorContext, resp);
     return resp;
   }
diff --git a/src/v0/destinations/marketo/config.js b/src/v0/destinations/marketo/config.js
index 16449ebbad..604be41dc0 100644
--- a/src/v0/destinations/marketo/config.js
+++ b/src/v0/destinations/marketo/config.js
@@ -14,24 +14,18 @@ const DESTINATION = 'marketo';
 const formatConfig = (destination) => ({
   ID: destination.ID,
   ...destination.Config,
-  customActivityEventMap: getHashFromArray(
-    destination.Config.rudderEventsMapping,
-    'event',
-    'marketoActivityId',
-    false,
-  ),
+  customActivityEventMap: destination.Config?.rudderEventsMapping
+    ? getHashFromArray(destination.Config.rudderEventsMapping, 'event', 'marketoActivityId', false)
+    : getHashFromArray(destination.Config.customActivityEventMap, 'from', 'to', false),
   customActivityPropertyMap: getHashFromArray(
     destination.Config.customActivityPropertyMap,
     'from',
     'to',
     false,
   ),
-  customActivityPrimaryKeyMap: getHashFromArray(
-    destination.Config.rudderEventsMapping,
-    'event',
-    'marketoPrimarykey',
-    false,
-  ),
+  customActivityPrimaryKeyMap: destination.Config?.rudderEventsMapping
+    ? getHashFromArray(destination.Config.rudderEventsMapping, 'event', 'marketoPrimarykey', false)
+    : getHashFromArray(destination.Config.customActivityPrimaryKeyMap, 'from', 'to', false),
   leadTraitMapping: getHashFromArray(destination.Config.leadTraitMapping, 'from', 'to', false),
   responseRules: destination.DestinationDefinition
     ? destination.DestinationDefinition.ResponseRules
diff --git a/test/__tests__/data/marketo_input.json b/test/__tests__/data/marketo_input.json
index 6a891fdea0..10fff935fc 100644
--- a/test/__tests__/data/marketo_input.json
+++ b/test/__tests__/data/marketo_input.json
@@ -170,11 +170,16 @@
           }
         ],
         "createIfNotExist": true,
-        "rudderEventsMapping": [
+        "customActivityPrimaryKeyMap": [
           {
-            "event": "Product Clicked",
-            "marketoPrimarykey": "name",
-            "marketoActivityId": "100001"
+            "from": "Product Clicked",
+            "to": "name"
+          }
+        ],
+        "customActivityEventMap": [
+          {
+            "from": "Product Clicked",
+            "to": "100001"
           }
         ]
       }