It’s hard to believe, but sometimes things don’t work as expected when integrating external systems with AX. When an error occurs during data exchange using AIF, the caller sees a generic “request failed” error. You can see the detailed error message in the Exceptions form by going to Basic > Periodic > Application Integration Framework > Exceptions.
However, you can configure AIF to display the full error message to the caller. Just go to the Endpoints form by navigating to Basic > Setup > Application Integration Framework > Endpoints. Then select the Propagate errors field to send the detailed error message back to the caller.
Detailed error messages may contain information that you don’t want external systems to see. If that’s the case, return detailed errors only while testing or for external systems that you trust.