I'm on a MAC 10.13.3 and I have these Unity versions installed in different named folders: Unity-5.3.4f1 Unity-5.5.2f1 Unity-5.6.5f1 The latest version is in the Unity/HUB/Editor folder 2017.3.1f1 I've installed the Unity HUB (Version 0.12.0), added all the Unity versions, and added all my projects. When I open a Unity-5.3.4f1 project using the Unity Hub, I get an empty project dialog window, there are TypeLoadException errors in the console, all the prefabs in the scene are missing, and the project shows no files. So, I try to open the same project with Unity-5.3.4f1 directly and get the empty project dialog window. The HUB has locked me out of working on this project which was working correctly before installing the HUB. Please help! UPDATE: I have uninstalled the HUB and it still keeps me from using Unity-5.3.4f1, I just see the empty project dialog window. I even reinstalled Unity-5.3.4f1 and still get this! From the HUB doc: This is not true! Opening Unity-5.3.4f1 Unity.app just shows a blank splash screen! UPDATE: Opening Unity-5.6.5f1 shows the login dialog. Login then opening Unity-5.3.4f1 fixes the project dialog. But, my project is still broken and rebuilding the project library doesn't seem to do anything. UPDATE: I upgraded my project to Unity-5.6.5f1 which fixed it!