I’m afraid that’s the problem. I can’t reinstall .net framework. It tells me that it is already installed – I just can enable or deable it. That’s all. I looked around and found this (https://knowledge.autodesk.com/support/autocad/learn-explore/caas/sfdcarticles/sfdcarticles/How-to-remove-and-reinstall-the-Microsoft-NET-Framework.html), which doesn’t work, because of this
“Note: Windows 8, 8.1, and 10 systems do not list “Microsoft .NET” as an installed program. Looking at “View installed updates” in Programs and Features in Windows 8 and 8.1 it may be possible to find the corresponding KB number and remove it that way. Windows 10 systems, however, with current updates from Microsoft, will not have any option to uninstall .NET. However, if your overall Windows Updates are not current, it may be possible to install the latest .NET version.”
I really don`t know what to do…