ScriptCS fails on launch (System.FormatException: The input is not a valid Base-64 string..."

[HoH-RussM]

ScriptCS works fine on all of my computers, and of colleagues, except one, where it receives an exception (pasted below).

It happens from any directory, cmd or powershell, admin or not. I can't figure out what's wrong.

I can run some things like scriptcs -help, and -version, but anything that would actually execute script, like -repl, or -scriptname gives this exception.

It says:
C:\Users\user>scriptcs
Unhandled Exception: System.FormatException: The input is not a valid Base-64 string as it contains a non-base 64 character, more than two padding characters, or an illegal character among the padding characters.
at System.Convert.FromBase64_Decode(Char* startInputPtr, Int32 inputLength, Byte* startDestPtr, Int32 destLength)
at System.Convert.FromBase64CharPtr(Char* inputPtr, Int32 inputLength)
at System.Convert.FromBase64String(String s)
at NuGet.EncryptionUtility.DecryptString(String encryptedString)
at NuGet.PackageSourceProvider.ReadCredential(String sourceName)
at NuGet.PackageSourceProvider.ReadPackageSource(SettingValue setting, Boolean isEnabled)
at NuGet.PackageSourceProvider.LoadPackageSources()
at ScriptCs.Hosting.Package.NugetInstallationProvider.GetRepositorySources(String path)
at ScriptCs.Hosting.Package.NugetInstallationProvider.Initialize()
at ScriptCs.Command.CommandFactory.CreateCommand(Config config, String[] scriptArgs)
at ScriptCs.Application.Run(Config config, String[] scriptArgs)
at ScriptCs.Program.Main(String[] args)