Azure Function throws internal server error 500

Question

Azure Function throws internal server error 500

Marco Vank 6

We have an Azure Function (Runtime V3) running a .NET Core 3.1 application.
On several occasions, we receive HTTP Status code 500 Internal Server Error when executing HTTP Functions.
I've looked in several logs (AppInsights Exceptions, Log System, Kudu => Host Logfiles) but have not been able to find the root cause of the error. It's running on the Consumption plan so it could potentially be a 'noisy neighbor'.

Is there some other log where I could find the actual root cause of the error?

JayaC-MSFT 5,606 Reputation points

2021-06-15T19:54:05.13+00:00

Hello anonymous user-4887 , Welcome to Microsoft QnA. Thank you for the question. Could you please provide the details I have asked for via private session.

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JayaC-MSFT 5,606 Reputation points

2021-06-15T19:54:05.13+00:00

Hello anonymous user-4887 , Welcome to Microsoft QnA. Thank you for the question. Could you please provide the details I have asked for via private session.

Answer 1

JayaC-MSFT 5,606

Hello anonymous user-4887 , thank you for sharing the details via private session.

I can see couple of System.NullReferenceException : Object reference not set to an instance of an object.
Please check in your code where you are binding values, else you may catch the System.NullReferenceException explicitly and log the details for which you are encountering the error.

Hope this helps!

Marco Vank 6 Reputation points

2021-06-17T13:21:59.767+00:00

Hi @JayaC-MSFT
there are indeed a couple of NullRefExceptions that occur in our code. I assume you saw them in AppInsight or File logs?
These exceptions actually happen somewhere inside the code that is executed when the HTTP Functions execute.
The errors with the 500 internal errors happen even before our code is being executed. When the client that calls the HTTP function, shows the 500 result, the actual HTTP Trigger function does not have any exceptions.

It's also important to note that when this 500 error happens, NO single Function is working at all. So at the same time, ALL HTTP Functions start returning 500 status code. And none of them is showing any logging.
Could you maybe see, if you can find something in the host logs? I'm assuming in the consumption plan (since it's shared), there are also logs that monitor all those functions on a level where tenants (like me) dont have access to.

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Azure Function throws internal server error 500

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