If you need to research error codes you can use this tool:
https://www.microsoft.com/en-us/down...aspx?id=100432
If there is an issue with load time linked DLLs I think the OS will just show some stupid code like 126 but I read that tools like ProcessMonitor or FileMon can reveal which DLL exactly is the problem.
Issues with installing VapourSynth are not exactly uncommon, restarting an app or the OS can help, or re-installing Python and VapourSynth.