HTTP Error 503 When Enabling 32-Bits Application in IIS

When enabling the 32-bits application mode in IIS, the application pool stops and and generate HTTP Error 503 indicating that the service is not available.

The problem might be due to corrupted IIS URL Rewrite module or incompatibility of the versions due to server upgrade. To resolve this issue, un-install the URL Rewrite module and re-install it again.

Resolve HTTP Error 500.19 - 0x8007007e

To fix this, disable the WSUS compression by running the following command on the server:

%windir%\system32\inetsrv\appcmd.exe set config -section:system.webServer/httpCompression /-[name='xpress']

To enable WSUS compression again by running this command:

%windir%\system32\inetsrv\appcmd.exe set config -section:system.webServer/httpCompression /+[name='xpress',doStaticCompression='false',dll='%windir%\system32\inetsrv\suscomp.dll']