Error Handling and alert for HTTP 401

Hi Experts,

We have an asynchronous ECC (Proxy) -> File via local processing. 1 of the outbound proxy message encountered 401 HTTP_RESP_STATUS_CODE_NOT_OK error and didn't reach PI. We have used exception class CX_AI_SYSTEM_FAULT in our program but the error was not caught.

1. Can we really catch this error via exception class CX_AI_SYSTEM_FAULT?

2. If not, how can we catch this error and also notify/alert us when such error occurred in ECC when sending the proxy message to PI?

3. Outbound proxy errors can only be handled in ECC itself and not in PI?

Has anyone done this before? Appreciate your inputs regarding this matter.

Thank you so much!

Mark