GAC appears to be broken on freshly installed Windows 10

Question

After repeatedly getting 2147024891 errors while trying to install some 3rd party controls, investigation shows that it is unable to install some DLL's into the GAC. I tried to find out why, and here are a few other symptoms I ran into:

• Browsing to C:\Windows\assembly gives an empty list.
• From the Developer Command Prompt (as admin), gacutil -l returns Number of items = 0
• Using a DOS Command prompt to list the contents of C:\Windows\assembly and C:\Windows\Microsoft.NET\assembly shows that there are quite some items installed.
• Nirsofts GacViewer tool shows 589 installed assemblies.
• Visual studio is running, can open and build solutions, only the WinForms designer has some quirks (probably related to missing items in the GAC?).

It looks like a permissions issue at first glance, but I am local administrator on my machine, so what could be the problem? Does windows 10 require any additional rights for manipulating the GAC that a "local admin" does not have by default?

If I rightclick, and choose "run as administrator" to open a command prompt, and then run:

gacutil -i myassembly.dll

Then I still get:

Failure adding assembly to the cache: Administrator permissions are needed to use the selected options. Use an administrator command prompt to complete these tasks.

Answer 1

After installing the Microsoft .NET Framework Repair Tool, all the problems disappeared.

Apparently disabling the Windows Search service can help in some cases, but that didn't work for me. The repair tool did.