Hello,
I've had this in the past on Windows Server 2012.
There's an issue with the DLL files not updating in the SIMS .net folder on the server. Deleted all dll files in the SIMS .net folder and then ran SIMSApplicationSetup.exe, SIMSManualSetup.exe, SIMSAmparkSetup.exe as administrator and this installed the latest dll files. SIMS is working again. The issue seems to be with permissions.