Hi @RajaputanaN ,

As we wont be able to find the root case with this window do the below...

Run the topic in Preview mode and check Show Logs option in preview. You should have a clear indication of the error being thrown.

In case you are still not able to figure out where the error is originating from, try placing gs.debug() messages in your flow and also maybe print variable values in gs.debug(). VA 'Show Logs' option renders gs.debug() messages, so you should get some leads on the root cause of the issue.