I've struggled with this one for a whole day, so here is both the problem & solution:

After profiling an ASP.NET application on Windows 7 (x64), I exited Visual Studio (possibly a crash) and installed some updates which required a reboot. When I loaded back up the ASP.NET Web Application in my Visual Studio Solution was dimmed out, and the Web & WAS services turned out to be stopped.

When I tried starting Windows Process Activation Service, I got the error "parameter is incorrect".

  • OMG! So I had an early work day (4am) and I happen to do 'something' that ran the perf mon in VS and then someone, it all broke. So THANK YOU so much for posting this. It helped and worked! Thanks MS for taking a year off my life.
    – user147372
    Nov 28, 2012 at 10:33

1 Answer 1


I tried the suggestion here and didn't have any success, so then I compared the registry entries for a working WAS service and one that wasn't. Here was that difference:


Not Working: Blank

Working: Cor_Enable_Profiling=0x0

Replacing the empty Environment value with Cor_Enable_Profiling=0x0 allowed the service to start and everything returned to normal. I believe profilers set that to 0x1 when they are profiling your application, it is possible it got deleted during the unexpected shutdown of my profiler.

  • 1
    PS - Had to do it with the IIS management service also: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\IISADMIN\Environment = 'Cor_Enable_Profiling=0x0'
    – user23596
    Dec 9, 2010 at 16:45
  • I had the very same problem. I was using the performance monitor of visual studio 11 developer preview. Seems it has kind of some issues. Anyway - your solution totally works for me - thanks! You made my day! :) Jan 20, 2012 at 9:11

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