title: .NET Runtime version 2.0.50727.5420 - Fatal Execution Engine Error (000007FEF9F5AF0E) (80131506) .Net Windows Service Crashing?
body: <p>I have searched around, googled a lot and read about similar errors. Also tried various solutions that have been posted here as well as on various forums around the world.</p>
  
  <p>I am getting the following error in event viewer when a .Net based Windows Service crashes:</p>
  
  <blockquote>
    <p>.NET Runtime version 2.0.50727.5420 - Fatal Execution Engine Error
    (000007FEF9F5AF0E) (80131506)</p>
  </blockquote>
  
  <p><strong>Detail:</strong></p>
  
  <blockquote>
    <p>Faulting application name: MyWindowsService.exe, version: 5.2.11.0,
    time stamp: 0x4e5201ae Faulting module name: mscorwks.dll, version:
    2.0.50727.5420, time stamp: 0x4ca2b7e1 Exception code: 0xc0000005
    Fault offset: 0x00000000006baa89 Faulting process id: 0x%9 Faulting
    application start time: 0x%10 Faulting application path: %11 Faulting
    module path: %12 Report Id: %13</p>
  </blockquote>
  
  <hr>
  
  <p>The My Windows Service terminated unexpectedly.  It has done this 13 time(s).</p>
  
  <p>The windows Service has been running fine since years. The windows service and its dependencies have not be updated since a couple of months. We have even commented all code within the service so in effect, we are left with just threads and timers that do nothing!</p>
  
  <p>The following references are imported into the windows service.</p>
  
  <pre><code>Imports System.Threading
  Imports System.Runtime.Remoting.Channels.Tcp
  Imports System.Runtime.Remoting.Channels
  Imports System.IO
  Imports System.Runtime.Remoting.Activation
  Imports Microsoft.Win32
  Imports System.Net
  Imports System.Runtime.Remoting
  Imports System.Data.SqlClient
  Imports System.Collections.ObjectModel
  Imports System.ServiceProcess
  Imports SearchOption = Microsoft.VisualBasic.FileIO.SearchOption
  </code></pre>
  
  <p>The operating system is <strong>Windows Server 2008 R2 x64.</strong> *<em>.Net Framework 3.5 Sp1</em>* is installed and no updates are installed except <strong>KB976902</strong> which i cannot un-install as neither via Control panel nor by command line as it says that it cannot be un-installed.</p>
  
  <p>We are facing this problem on a couple of servers and these issues have started popping up in last couple of days. We have even tried deploying an older build of the windows service as well as commenting out the functionality in each thread but to no effect!.</p>
  
  <p>The problem is also occurring where Windows Update was installed and all windows updated were being installed as well as those which had windows update disabled and no other update except <strong>KB976902</strong> was installed. We have some servers where this crash is NOT occurring at all and those servers have this update <strong>KB976902</strong> installed as well.</p>
  
  <p>We have tried updating .Net framework upto .Net 4.0 with all its updates as well on a couple of servers but that does not change anything. All Windows Servers are genuinely licensed and there is no such issue of Administrative privileges problem.</p>
  
  <p>Kindly help.</p>
  
  <p>Thanks.</p>