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Profiler not starting



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We’re trying to use the thread profiler for the first time.

We have the agent running on a Windows server where a .NET console application is running. We are having some performance issues with this application in certain scenarios and are trying to debug the problem.

I can see the application in the New Relic UI and can click the “Start Profiling” button. However, the UI then remains in the state: “Waiting for instance to start profiler…”. It never begins.

Any ideas on what steps we might take to get the profiler to start?




Hi @Luke.Ferris are there any other profilers running against your application? .Net only allows one profiler to be attached.


I have the exact same problem running on .Net app working as a service


Hi guys,

So I was originally trying to use the Visual Studio profiler but that failed because the environment variable “COR_PROFILER” was already set to the NewRelic GUID.

Furthermore, I note that I also can’t connect the Thread profiler to another instance of the same application (not a service incidentally, I’m not sure per Joel’s comment whether this makes a difference) on another server where no other profiling tools are present.

Any thoughts on what I might do to collect more information on the problem? If it helps the application is an instance of job scheduler.




Hi @Luke.Ferris,

The thread profilier not starting is a known issue we are tracking internally at this time. We will update this forum post when there is a status change.

Thanks for using the New Relic forum.


Hi, I apologize for necroposting but we’re consistently seeing this issue with some of our .NET apps even now 3 years after the last post, where we get very inconsistent results. Sometimes we can start a thread profiler and it starts within a minute, sometimes we wait 10-15 minutes and it never starts. Is this still being tracked internally as an issue? Has there been any update on it?

Alternatively, is there any way to manually trigger a thread profiler on the server itself rather than through the NR UI?


Hi @ryan.zink,

There have been a few issues with the thread profiler since the original post, but many have been resolved since then.

Still, we do get an occasional report of the thread profiler timing out.

Can you provide a permalink to your thread profiler that is timing out, so our support folks can take a look?

One thing to note that you may be aware of is that .NET Core apps in Linux do not include this feature yet. There’s not a way to manually trigger the thread profiler outside of the UI.

I’ve found that the most consistent way to ensure the thread profiler doesn’t time out is to make sure the application is being exercised with a good deal of traffic while it runs, and that it will work best when the application has already been running for at least a few minutes.

I’ll look out for your link, and we might need to make a ticket out of this and request debug level logs to investigate the issue you’re running into.


Hi @ntierney, sorry for the late reply, didn’t see it until now.

I don’t see a way to permalink to the specific instance of the profiler that times out, but this is the application that we frequently see fail to start. It is an ASP.NET 4 IIS application that has constant traffic throughout the day, particularly during the time periods when we are trying to initiate the profiler.


Hi @ryan.zink,

I’ve gone ahead and spun up a ticket to investigate this. I’ll send you an update in the case with next steps. Once we reach a resolution there, we can share what that is back here for everyone’s benefit.

~ @jlangdon