On windows 2008/IIS a asp.net page with heavy processing gets called every hour. If that server is doing nothing else it's fine. If the server is handling other web requests at the same time we get this error occasionly:

.NET Runtime version 2.0.50727.4016 - Fatal Execution Engine Error (000007FEF630A5C6) (80131506)


Faulting application w3wp.exe, version 7.0.6002.18005, time stamp 0x49e03238, faulting module mscorwks.dll, version 2.0.50727.4016, time stamp 0x49cc56fb, exception code 0xc0000005, fault offset 0x000000000019734e, process id 0x%9, application start time 0x%10.

And then iis dies and restarts. How can I get more information about what's causing this error and how to fix it?

  • I have phoned microsoft and started an incident. If they can work out the cause I will post it back here.
    – horatio
    Dec 11, 2009 at 2:15

4 Answers 4


According to Tess Ferrandez:

Fatal Execution Engine Exceptions

Fatal Execution Engine Exceptions are fairly rare, but when they occurr it's normally a bug. This means that for some reason we went into some piece of code that we were not supposed to in the CLR and the CLR has decided that in the unlikely event that someone comes in here, let's throw a Fatal Execution Engine exception and die because we can't recover from this point. In the eventlog this will be logged as Execution Engine Exception occurred and the address listed will tell exactly where in the code it occurred. If you reach one of these and can't find a knowledge base article about it, contact support, preferably with a crash dump available since that will speed up the time to resolve the case tremendously.

She also has lots of information on her blog about generating crash dumps, etc, etc for debugging purposes.


That's likely not an easy error to track down. Some places that I should looking are:

  • IIS logs, see if you can tell what happened just prior to the issue
  • Event Viewer, it's possible that it's a hardware issue and you've touched on bad memory
  • Hardware vendor's hardware logs
  • Turn on Failed Request Tracing and see what's logged just before the error
  • See if you can catch the error with Debug Diag and get a dump as the issue occurs

Have you tried to run your application with other .NET Framework version installed on server? If .NET Runtime version 2.0.50727.4016 is important for you - may be this KB article (and patch availible) will help you...


Microsoft say it's this issue:


They have given me a fix. I haven't tried it yet but I will soon...

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