The 500.19 IIS Error can happen when WSUS is installed on the same box as Recast Management Server and is caused by WSUS installing a 64-bit version the DynamicCompressionModule but not the 32-bit version.
To fix the issue, you can either disable the XPress compression scheme for all pages and application pools, disable loading the XPress module for 32-bit application pools, or install the 32-bit version of this module.
Disable XPress compression for all pages and application pools
Run the following command to disable XPress compression globally. %windir%\system32\inetsrv\appcmd.exe set config -section:system.webServer/httpCompression /-[name='xpress']
Disable XPress for 32-bit application pools
Edit the C:\Windows\System32\inetsrv\config\ApplicationHost.config file and add the following line in the section.
Install the 32-bit version of suscomp.dll
Install WSUS on a 32-bit machine and copy the suscomp.dll file from that machine to %windir%\SYSWOW64\inetsrv\