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We have a few APIs that are being long polled through Azure API Management. For some reason, we are receiving a response of 200 [not sent in full (see exception telemetries)] and then a System.Exception: A task was canceled. exception in App Insights.

Taking a look at the server app service telemetry, the requests were completed without any exception there.

Can anyone help me figure out what this status response means and why are we getting this exception?

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Pratik
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1 Answers1

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These errors mean that APIM started to send response to client, sent status code and description, and some portion of headers and body. These traces must be accompanied by exception telemetry as response code suggests. Depending on what you see there it may be:

  • Client connectivity error - client terminated connection before response was sent in full
  • Backend connectivity error - backend terminated connection before providing full response

The reasons for both may vary a lot, but given small duration I'd suspect that it's client closing connection. One of the reasons for this, for example, is if this API is used from browser it is normal for browser to terminate connection and abort reading response if user navigates away from page that made the call.

Vitaliy Kurokhtin
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