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c#azureexceptionazure-functionserror-logging

Azure functions V3 logging exceptions in startup file

Currently we are preapring a set of azure functions to trigger a blob storage. The function app V3 should do some kind of checks on startup. So I added the Startup.cs file in the VS solution. The problem what I'm having is that sometimes exceptions happen while performing these checks in the startup file. But I never find these exceptions in azure portal (application insights/exceptions). I tried many ways to implement logging there, but unfortunately the app keeps saying Host is not running without any logging in these logs:

enter image description here

I'm not talking about the logs of a specific function, I mean here the logs of the function app on startup.

This is the code where it throws the exception in startup.cs:

try
{
   // async method CheckSomeBlobsFiles
   CheckSomeBlobsFiles(connectionString, 
       blobContainerName, blobDirectoryName).GetAwaiter().GetResult();
}
catch (Exception e)
{
   throw new Exception($"Error while checking database schemas: {e.Message}");
}
Solution

  • After some research, for the exceptions from Startup.cs, you can find it in azure portal -> Diagnose and solve problems blade.

    The steps as beow:

    1.Nav to azure portal -> your function app -> on the left side, click on Diagnose and solve problems -> then input function app down in the search box -> then click on the Function App Down or Reporting Errors. The screenshot as below:

    enter image description here

    2.In the new page of Function App Down or Reporting Errors, expand Function Executions and Errors -> then expand Detected host offline in your function app. Then you can see the exceptions in the startup.cs are logged there(if it's not there, please specify a proper time range on this page). The screenshot as below:

    enter image description here