kindly find the error i am not able to login to studio main page
I had a quick search and it seems to be related to either nuget packages and/or netframework:
Visual Studio Feedback
I would suggest first to try and clear these two folders:
%userprofile%\AppData\Local\UiPath\.cache
%userprofile%\.nuget\packages
Feel free to backup both folders beforehand.
Could be a couple of things, my suggestion here would be to create a copy of your project.json file (or rename it) and then try to open again Main.xaml.
UiPath is trying to read the project.json file and does not understand its content.
When you rename or delete it, it will re-create the file, with the only downside that you’ll need to re-install the packages (But since you renamed the previous faulty file, you should have them listed there, and it will be an easy fix).
BR,
Ignasi