System.NullReferenceException in /_/src/Sentry.AspNetCore/SentryMiddleware.cs in roughly 1 in 100 requests

Environment

Sentry SaaS (sentry.io) Sentry SDK: .NET 3.3.4 Framework: ASP.NET Core 5.0 Deployed to Azure Web Apps

Steps to Reproduce

This issue only occurs sporadically (1 in 100 requests) and has only occurred 2 days after upgrading to 3.3.4. I wasn’t able to reproduce this issue locally and so far has only occured on our Azure hosted instances.

1. Inside Program.Main() we call webBuilder.UseSentry() with the generic .NET Host builder (source for reference)
2. Inside our Controller we call SentrySdk.ConfigureScope() like so:

public async Task<ActionResult<FullLessonData>> FetchLessonByLessonID(long lessonID)
{
    var (status, lesson) = await _lessonModelGenerator.LessonByID(lessonID, User);
    SentrySdk.ConfigureScope(scope =>
    {
        scope.SetExtra("lessonModelGenerator.responseStatus", status.ToString());
    });
    return status switch
    {
        LessonModelGenerator.ResponseStatus.OK => lesson == null ? Forbid() : Ok(lesson),
        LessonModelGenerator.ResponseStatus.NoAccess => Forbid(),
        LessonModelGenerator.ResponseStatus.NotFound => NotFound(),
        _ => throw new NotImplementedException("LessonModelGenerator.ResponseStatus is not handled")
    };
}

1. In roughly 1 in 100 requests, we receive a System.NullReferenceException in File "/_/src/Sentry.AspNetCore/SentryMiddleware.cs", line 139, col 9, in async Task SentryMiddleware.InvokeAsync(HttpContext context) (The full sentry log + callstack for reference.)

Expected Result

No exception is thrown during normal operations

Actual Result

Raw JSON of the sentry event that captures the exception including callstack

[jan-auer]

metadata indeed comes from the ingestion pipeline. It is generated here and written here. They are used by the Sentry UI to render issue titles among other things.

They are definitely unrelated to any SDK problems.

[SimonCropp]

@bruno-garcia so based on that, this should be closed as not related to sentry?