Hi I have an APIM with backends created. These backends point to an Azure Function App. I am receiving frequent logs like The underlying connection was closed: A connection that was expected to be kept alive was closed by the server. A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond Client connection was unexpectedly closed. Can you please help me with the possible fixes... ? Thanks

@Abhay Chandramouli Thanks for reaching out. Please refer to my blog which explains in detail about all these scenarios. https://techcommunity.microsoft.com/t5/azure-paas-blog/troubleshooting-4xx-and-5xx-errors-with-azure-apim-services/ba-p/2115744 do let me know incase of further queries, I would be happy to assist you.

Azure APIM | Connection issues

Abhay Chandramouli 966

I have an APIM with backends created. These backends point to an Azure Function App.

I am receiving frequent logs like

The underlying connection was closed: A connection that was expected to be kept alive was closed by the server.
A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond
Client connection was unexpectedly closed.

Can you please help me with the possible fixes... ?

Thanks

JananiRamesh-MSFT 21,471 Reputation points

2024-04-24T05:05:15.7766667+00:00

@Abhay Chandramouli did you get a chance to see my previous response? do let me know incase of further queries, I would be happy to assist you.
JananiRamesh-MSFT 21,471 Reputation points

2024-04-29T06:16:09.36+00:00

@Abhay Chandramouli Just following up to check if the below answer helped. If that answers your query, do click Accept the answer for the same, which might be beneficial to other community members reading this thread. And, if you have any further query do let us know. I would be happy to help.

1 answer

JananiRamesh-MSFT 21,471 Reputation points

2024-04-23T12:25:52.3866667+00:00

@Abhay Chandramouli Thanks for reaching out. Please refer to my blog which explains in detail about all these scenarios.

https://techcommunity.microsoft.com/t5/azure-paas-blog/troubleshooting-4xx-and-5xx-errors-with-azure-apim-services/ba-p/2115744

do let me know incase of further queries, I would be happy to assist you.
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Abhay Chandramouli 966 Reputation points

2024-04-24T05:13:09.2966667+00:00

Hi @JananiRamesh-MSFT ,

I saw you doc, it was helpful. But I can see this is a known apim issue and is there anyway to mitigate the issue without using the retry policy ?

The question being if the connection is terminated post forward to backend, process happens in the backend but the consumer sees an error.

JananiRamesh-MSFT 21,471 Reputation points

2024-04-24T08:54:54.7166667+00:00

Abhay Chandramouli Thanks for getting back, this is by product design and currently no other way to mitigate it.

If the connection is terminated after the request has been forwarded to the backend service, then the backend service will still process the request and generate a response. However, if the connection is terminated before the response is received by APIM, then the consumer may see an error. The best way to mitigate this issue is to use the retry policy in APIM, which is specifically designed to handle these types of errors.

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