!CreateDirectoryRecursive(fullpath) error how to fix

Hi i will start unity and then came when i open a project or i create a project and open it then came this message: !CreateDirectoryRecursive(fullpath) my idear is reinstall unity compleetly but where the other unity files why when i deinstall uniy with iobit uninstaller the i reinstall it the project are there again and i open it and i crash my problem is i must uninstall unity completly and reinstall it.
thanks for the suport.
sorry for my not so good english iam from germany when you something dont understand than ask it please.