Breakpoints are ignored when debugging in Visual Studio 2008 on 64-bit system

Question

I'm trying to debug an ASP.NET web application in this environment:

• Windows Server Standard 2008 SP2 x64
• Single-core CPU
• 4GB RAM
• Visual Studio 2008 with Remote Debugger SP1
• .NET 3.5 Web Application running in IIS in 64-bit mode

The code I am trying to debug is a simple event handler with some basic sequential code.
What I observe is that breakpoints get randomly ignored and VS often exits debug mode when I try to step through the code. The code is compiled in debug mode.

EventViewer shows no warning or error messages that would relate to this. I am certain that this is not caused by IIS app pool recycle/reset.

I've tried all the usual steps: iisreset, reboot VM, rebuild solution, reinstall Visual Studio.

Any ideas?

Answer 1

Maybe your IIS App Pool is recycling for some reason once in a while. This kills the IIS worker process and therefore unhooks the debugger.

You can check if this happening in the Eventlog. Also check you application pool settings in IIS Manager.

Answer 2

Got the same problem with randomly missed breakpoints and debug mode resuming/stopping when stepping through, on a WPF application though. This fix solved it:

http://code.msdn.microsoft.com/KB957912

Answer 3

Could not find a solution.

Worked around this behaviour by using a combination of Debug.Print() and Sysnternals DebugView

Hope this helps.

Answer 4

I had the same problem with a Windows Form application, and I applied the same hotfix as Julien did. (http://code.msdn.microsoft.com/KB957912). I haven't had the problem since.