Mule Exception Payload
did you try with getExceptionMessage().
Note point here is when exception occurs payload will be lost in the mule message. You have to store payload in session var to get it during the exception case.
I'm testing my REST API on Mule ESB, and when the API, implemented using Python Flask, returns a 200 http status Mule correctly exhibits the message returned (a JSON, as it is expecting). But when I return any other status, I can't seem to exhibit the message returned, which is a string. 
I'm trying to configure the exception thrown to show the original message returned by the API. How can I access it? I'm using Anypoint Studio.
Thanks in advance.