diff --git a/doc/testing/testplan/vendor_extensibility/README.md b/doc/testing/testplan/vendor_extensibility/README.md
index 53d58f23fdd786d72e1ef7218712a9242754bac1..bbc8f5673d881e8df77fb3d7d6f1cb5ecc6abdf4 100644
--- a/doc/testing/testplan/vendor_extensibility/README.md
+++ b/doc/testing/testplan/vendor_extensibility/README.md
@@ -219,8 +219,8 @@ At this documentation you will have all information and related files and exampl
      2. Error Response Body must accomplish with **ProblemDetails** data structure with:
         * status 400
         * title with message "Bad Request"
-        * detail with message "VendorExt feature active at Supported Features but VendorSpecifics parameters not published".
-        * cause with message "VendorExt feature active but vendorSpecifics not present".
+        * detail with message "If and only if VendorExt feature is enabled, then vendor-specific fields should be defined".
+        * cause with message "Vendor extensibility misconfiguration".
 
 ## Test Case 5: Publish API with vendorExt inactive but with vendorSpecifics
 
@@ -262,8 +262,8 @@ At this documentation you will have all information and related files and exampl
      2. Error Response Body must accomplish with **ProblemDetails** data structure with:
         * status 400
         * title with message "Bad Request"
-        * detail with message "VendorExt feature inactive at Supported Features but VendorSpecifics are present parameters published".
-        * cause with message "VendorExt feature inactive but vendorSpecifics present".
+        * detail with message "If and only if VendorExt feature is enabled, then vendor-specific fields should be defined".
+        * cause with message "Vendor extensibility misconfiguration".
 
 
 ## Test Case 6: Published API without vendor extensibility discover with VendSpecQueryParams enabled
@@ -485,8 +485,8 @@ At this documentation you will have all information and related files and exampl
      2. Error Response Body must accomplish with **ProblemDetails** data structure with:
         * status 400
         * title with message "Bad Request"
-        * detail with message "supportedFeatures must be present in this request".
-        * cause with message "supportedFeatures missed".
+        * detail with message "supportedFeatures not present in request".
+        * cause with message "supportedFeatures not present".
 
 
    [service api description]: ../api_publish_service/service_api_description_post_example.json  "Service API **Description** Request"