History JSON does not have a workflow ID, so it won’t be accurate in a replayer. If you need accurate workflow ID during replay, instead of ReplayWorkflowHistoryFromJSONFile, you need to call ReplayWorkflowHistoryWithOptions with the ReplayWorkflowHistoryOptions.OriginalExecution set with the proper ID. Granted this call accepts a proto history object instead of a JSON file, so you’ll have to use something like jsonpb.UnmarshalString to turn JSON to History proto object.