TwinCAT project build fails with unspecified error

Question

My TwinCAT PLC project was working fine, but suddenly one day it could not build at all. The error message is simply "The operation could not be completed. Unspecified error".
I also noticed that all my local files, such function block files, would have yellow triangle symbols with an exclamation mark next to them.
If I wanted to start a new project, I would get an exception on _3S.CoDeSys.UserManagement.UserAuthentication.

Answer 1

After a lot of struggle, I finally fixed the problem, sort of.
Apparently, the problem is related to the FipsAlgorithmPolicy register. The register is used to certify cryptographic software. I am not sure whether it is TwinCAT that is not made to comply with that or my PLC project is not up to that standard.

Anyway, to fix the problem:

Type register editor in Windows Start, right click and choose run as an admin.

In register editor, go to HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Lsa.

Under a subkey you should see FipsAlgorithmPolicy. Changed the "enabled" value to 0 or simply delete this register. Restart Visual Studio.