Exception messages are not logged when the message exceed max length

[ravibha]

Hi all,
We are observing an issue with logging of exceptions in ApplicationInsights, when the message length is > 32K limit.
My expectation is if the messages are greater than the limit, they should be truncated by the sdk and logged to appinsights. However, I don't see that happening. Instead I don't see an exception logged in appinsights. I do see a trace logged though.

Is this a known issue?

For now, the workaround I am using is to create a ExceptionTelemetry object with truncated message and call TrackException(ExceptionTelemetry exceptionTelemetry)

I did notice, there is a Sanitize method for ExceptionTelemetry. Not sure if it is called.

[ravibha]

I also hit a similar issue when there are AggregateExceptions with long inner exception messages or a lot of inner exceptions, the exceptions are not logged in appinsights. Looks like both might have the same cause.

Package versions:

<PackageReference Include="Microsoft.ApplicationInsights.AspNetCore" Version="2.17.0" />
<PackageReference Include="Microsoft.NET.Sdk.Functions" Version="3.0.11" />

Below is a simple repro with a Azure function. In the catch block, the trace is logged with the AggregateException but I don’t see any exceptions being logged. Would be great to have a fix or a workaround for this.

public static class Function1
    {
        private static TelemetryClient telemetryClient;
        private static string ExceptionText ="<Some long text>";
 
        [FunctionName("Function1")]
        public static void Run([TimerTrigger("0 */1 * * * *")]TimerInfo myTimer, ILogger log)
        {
            log.LogInformation($"C# Timer trigger function executed at: {DateTime.Now}");
            var telemetryProperties = new Dictionary<string, string>();
            telemetryProperties.Add("KeyResultId", "2323");
            telemetryClient = new TelemetryClient(new TelemetryConfiguration { InstrumentationKey = "2c43572f-e11d-4d0b-a053-761a3387a225" }); 
            telemetryClient.TrackTrace("Trace from azure function"); 
            Action<int> job = i => throw new TimeoutException(ExceptionText); 
            // we want many tasks to run in parallel
            var tasks = new Task[100];
            for (var i = 0; i < 100; i++)
            {
                int j = i;
                Task task = Task.Run(() => job(j));
                tasks[i] = task;
            }
 
            try
            {
                // wait for all the tasks to finish in a blocking manner
                Task.WaitAll(tasks);
            }
            catch (Exception ex)
            {
                telemetryClient.TrackTrace($"Exception: {ex}");
                telemetryClient.TrackException(ex, telemetryProperties);
            }
        }
    }

Thanks!

[andystumpp]

Any update on this, can we prioritize? This seems critical for troubleshooting and should be covered in the SDK without having manual code to work around this?

[cijothomas]

related: #2482

[Daniel-Guenter]

This is an issue for us as well. The only way we can work around it is with reflection.

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