Azure APIM - ProtocolViolation: at forward-request

Question

We are observing intermittent ProtocolViolation: at forward-request error for a backend call from Azure APIM. The Appinsights shows error message as
The server committed a protocol violation. Section=ResponseStatusLine

Any pointers on what could be going wrong. I checked a few posts on stackoverflow - most of them pointed to CRLF issues/malformed headers and change webserver settings to useUnsafeHeaderParsing to true
Is there a way to resolve this in APIM?

Answer 1

Hi @Nagashree Balasundaram Thanks for reaching out. No, there is no way to resolve it from APIM because this is not APIM's problem this happens due to your backend replies with broken payload. You need to take a look at your backend to understand under which conditions this would happen. If there is any firewall/gateway between APIM and backend that is a good place to start. Logging network traffic usually helps, although it would need to be decrypted.

let me know incase of further queries, I would be glad to assist you.

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