'Issues after VS2022 installation

I installed Visual Studio 2022 and cloned one of my "older" projects from Github.

It is based on .NET Framework 4.5. While cloning it, it asked me if I want to "convert" it to .NET 4.8. I clicked yes.

Now I get these errors:

Screenshot 1

Screenshot 2

Any ideas?

Thanks in advance

EDIT: Screenshot from first errors



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