Can't get message associated to 503 error in REST

I face an issue by using a REST connection. I tried to contact a WM REST service from another WM application.
When the Rest service simulate http 503 error, I can’t get the message associated with the errorcode.
With errorcode 500 or 502 (for example)I’m able to get the linked message.
Do you know I can get the error message for 503?

Best Regards

Hello Adrien,

Are you referring to REST connector or REST API, can you be more specific or share the API information.