Apps failing to start, how to reset .NET Frameworks' Global Assembly/Access Cache ? #GAC

Question

i added some Assemblies to .NET Framework's Global Access Cache, by a not-overwriting command of gacutil.exe . and some apps stopped working, 1 of them showed this error:

Unhandled Exception: System.TypeLoadException: Could not load type 'System.Diagnostics.Process' from assembly 'System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=<<..>>'.
   at Microsoft.CodeAnalysis.CSharp.CommandLine.Program.MainCore(String[] args)
   at Microsoft.CodeAnalysis.CSharp.CommandLine.Program.Main(String[] args)

removing the added content didn't help .

but after reinstalling .NET Framework 4.8 Runtime i started getting this error instead

error CS7065: Error building Win32 resources -- Could not load type 'System.Numerics.BigInteger' from assembly 'netstandard, Version=2.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51'.

i also catched this

System.TypeLoadException: Could not load type 'System.ComponentModel.DataAnnotations.ValidationResult' from assembly 'System.ComponentModel.DataAnnotations, Version=4.0.0.0, Culture=neutral, PublicKeyToken=<<..>>'.
   at McMaster.Extensions.CommandLineUtils.CommandLineApplication..ctor(CommandLineApplication parent, IHelpTextGenerator helpTextGenerator, CommandLineContext context)

how to fix this ?

Answer 1

solution:

• i allowed access to %windir%\Microsoft.NET\assembly by changing it's permissions, then terminated all Explorer processes and moved all content of the folder out to temp folder .
• ran sfc /SCANNOW in Elevated Command Prompt, it restored GAC_MSIL and fixed 1 app .
• copied other folders back to the assembly and that fixed the other ones .