Runtime fatal error - possibly CLR bug

Question

I would like some insight into an error I'm receiving:

Managed Debugging Assistant 'FatalExecutionEngineError' has detected a problem in 'C:\app.exe'. Additional Information: The runtime has encountered a fatal error... This error may be a bug in the CLR or in the unsafe or non-verifiable portions of the user code. Common sources of this bug include user marshaling errors for COM-interop or PInvoke, which may corrupt the stack."

I would like to understand not only the error itself, but what/how CLR may play a part, and I've never really heard of COM-intercop or PInvoke are.. so some insight into those would also be helpful.

Also, the really odd part of it all is that if I continue through the breakpoints and do not step into or over, I do not see the error. However, if I step through line by line, the error pops up! Can anyone explain why I only see it while stepping through?

Not sure what other information would be useful.. please let me know (nicely of course!) what I could add.

Thank you in advance! :)

Answer 1

I ran into this working on a Dotnet Core project. I deleted the binaries and rebuilt, this fixed it for me. Simply doing a Clean and Build or just Rebuild had no effect.

Answer 2

It's most likely not a CLR bug, but probably a Heisenbug. We can't really say what's causing it, though, without seeing your code.

Try turning on Managed Debugging Assistants to figure out if some error or access violation is being suppressed.