It is not possible to install packages

I have installed studio, but whenever I try to add a package I get an error with the message:
System.ArgumentOutOfRangeException: Specified argument was out of the range of valid values.
Parameter name: supportedFrameworks

I looked in the forum and forund this topic I installed all the packages for activities in UiPath but activities are not coming under activity section but following the advice did not help.

There are no empty supportedframeworks folders in C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETPortable

I have uninstalled Studio, removed the content of the UIpath folders in appdata local and roaming. And reinstalled studio.

Have you tried to uninstall all versions of .net framework in you machine and reinstall latest version of dotnet from microsoft website (4.7.1 something) .? then try to install your UiPath Studio.?