I have set up a server using IIS on Windows Service 2016 using python FastAPI with uvicorn. Sending individual querying works well, but I had been moving to testing the API with parallel queries using k6. I had been sending queries with 30 VU across 1min with a random sleep between, resulting in around 2.1 requests/sec. However I noticed that the service had been having sporadic 502.3 errors about 15% of the time.
The error codes tagged to it were: 12030 and 12152. According to https://learn.microsoft.com/en-us/windows/win32/winhttp/error-messages:
ERROR_WINHTTP_CONNECTION_ERROR
12030
The connection with the server has been reset or terminated, or an incompatible SSL protocol was encountered. For example, WinHTTP version 5.1 does not support SSL2 unless the client specifically enables it.
ERROR_WINHTTP_INVALID_SERVER_RESPONSE
12152
The server response cannot be parsed.
The failure percentage seems to scale with higher number of requests per second.
I had checked the httperr logs under C:\Windows\System32\LogFiles\HTTPERR, but only saw Timer_ConnectionIdle which I read to be not an issue.
How else can I troubleshoot these error 502.3 to see what the issue is?
UPDATE 2022/12/20:
Managed to get the FRT for one of the occurrences. How to proceed to troubleshoot? It does seem to be just indicate 502.3 error
Event: MODULE_SET_RESPONSE_ERROR_STATUS
ModuleName: httpPlatformHandler
Notification: EXECUTE_REQUEST_HANDLER
HttpStatus: 502
HttpReason: Bad Gateway
HttpSubStatus: 3
ErrorCode: 2147954552
