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Calling LoadLibraryEx on ISAPI filter “C:\Windows\Microsoft.NET\ Framework\v4.0.21006\ aspnet_filter.dll” failed

By Jesse | January 24, 2011

If you get the error ‘Calling LoadLibraryEx on ISAPI filter “C:\Windows\Microsoft.NET\Framework\v4.0.21006\aspnet_filter.dll” failed’, it can be fixed by opening IIS manager (start–>run–>inetmgr)  and then going down to the websites section.  Click on the appropriate website then select ISAPI Filters.  under ISAPI filters click on the ASP 4.0 filter and select the remove button.  this will remove the ASP.NET 4.0 ISAPI filter.  Unless you have a product that you know needs 4.0 you are fine.

I have not yet encountered a problem that requires the 4.0 filter remain in place.

To restore the filter, you would just click add, type a friendly name for the filter then point it back to the file : C:\Windows\Microsoft.NET\Framework\v4.0.21006\aspnet_filter.dll.   this would return the server back to the state it was in before you removed it.

After removing the filter do an IIS reset from the command prompt (iisreset).

This error may sometimes be encountered after installing ASP.Net 1.1 on a Server 2008 system but could also occur at other times.  Removing the filter does not harm the machine in any way since the process is reversible.

Calling LoadLibraryEx on ISAPI filter “C:\Windows\Microsoft.NET\Framework\v4.0.21006\aspnet_filter.dll” failed

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Topics: Uncategorized | 4 Comments »

4 Responses to “Calling LoadLibraryEx on ISAPI filter “C:\Windows\Microsoft.NET\ Framework\v4.0.21006\ aspnet_filter.dll” failed”

  1. Polshgiant Says:
    July 13th, 2011 at 11:51 pm

    This was exactly my problem. Thanks for sharing.

  2. Gangadhar Says:
    October 19th, 2012 at 10:43 am

    Thanks a lot

  3. Erik Says:
    October 25th, 2012 at 10:15 am

    Removing it from ISAPI filters and then adding it again solved the problem for me. Thanks!

  4. Guillermo Says:
    March 21st, 2013 at 12:57 pm

    Excelente, justo lo que buscaba, me ocurrio despues de intentar instalar net framework 1.1