HTTP Error 500 - Internal Server Error

Question / Problem

HTTP Error 500 - Internal Server Error

Answer / Solution

Possible Reason 1: The 'ASP.NET Impersonation' is enabled for the site.

Solution: Disable the 'ASP.NET Impersonation':

1. Start the IIS-Manager.
2. Navigate to the site of the SpaceObServer Web Access
3. In the middle pane, in section IIS choose 'Authentication'.
4. Deactivate the 'ASP.NET Impersonation'.
5. Restart the site.

Possible Reason 2: The web service tried loading a 64 bit DLL. This is however not possible, since the 'Application Pool' of the SpaceObServer web service is configured to run 32 bit Applications only.

Solution: We have to prevent loading 64 bit DLLs:

1. Open a command line prompt with Administrator permissions.
2. Execute: IISRESET /STOP
3. Open the file "applicationHost.config" in "C:\Windows\System32\inetsrv\config".
4. Search for tags named "<add>" and "<filter>" matching the DLL, e.g.:
   
   <add path="C:\Program Files\Microsoft\Exchange Server\V14\ClientAccess\owa\auth\owaauth.dll" allowed="true" groupId="MSExchangeClientAccess" description="Microsoft Exchange-Clientzugriffsserver" /> <filter name="Exchange OWA Cookie Authentication ISAPI Filter" path="C:\Program Files\Microsoft\Exchange Server\V14\ClientAccess\owa\auth\owaauth.dll" enabled="true" />
5. Add the attribute preCondition="bitness64" to these tags, e.g.:
   
   <add path="C:\Program Files\Microsoft\Exchange Server\V14\ClientAccess\owa\auth\owaauth.dll" allowed="true" groupId="MSExchangeClientAccess" description="Microsoft Exchange-Clientzugriffsserver" preCondition="bitness64" /> <filter name="Exchange OWA Cookie Authentication ISAPI Filter" path="C:\Program Files\Microsoft\Exchange Server\V14\ClientAccess\owa\auth\owaauth.dll" enabled="true" preCondition="bitness64" />
6. Save the file.
7. Execute: IISRESET /START