Application Insights: TelemetryChannel found a telemetry item without an InstrumentationKey.

When reviewing some log messages inside Application Insights I noticed a lot of messages like this:

AI: TelemetryChannel found a telemetry item without an InstrumentationKey. This is a required field and must be set in either your config file or at application startup.

I had an ApplicationInsights section inside my appsettings.json where I provided an instrumentation key, so that could not be the issue(and the trace message arrived in the correct Application Insights resource).

	{
	"ApplicationInsights": {
	"InstrumentationKey": "instrumentation-key"
	}
	}

view raw appsettings.json hosted with ❤ by GitHub

	public void ConfigureServices(IServiceCollection services)
	{
	services.AddApplicationInsightsTelemetry();
	}

view raw Startup.cs hosted with ❤ by GitHub

This turned out to be a bug in the Application Insights version I was using(2.15.0).

Upgrading to the latest version(2.20.0 at the moment of writing) solved the problem.

Up to the next issue!