All unity UI component are changed in Missing script (mono script)

Hello everyone,

I really need help because i'm encountering a big issue. I've changed my project from Unity 2018 to 2019 because we needed to check some compatibility in some asset. We had a lot of issue in 2019.2.2 (Assembly broken, ect...) so we deleted our library folder / reimport asset / delete manifest.json, it didn"t work. We downgrade our project back to 2018.3.2f1, and it appears that all the UI Unity component are missing. Is there a way to repare the references / dependencies without having to re add the component by hand.

Thank you everyone,

 

Unity doesn't support downgrading Unity versions. When you upgrade Unity versions there are scripts Unity runs to convert any data structures which have changed in your project files to new versions Unity internally uses in the new Unity version. There is no system for reversing the process for a downgrade (how would the old version of Unity even know the data structures used in the new version of Unity anyway?).

So the best way of handling this is to just use version control to revert your entire project to just prior to your Unity upgrade. You'll probably want to again delete your library folder. If you're not using version control, you'd restore your project from the backup you should have created before the Unity upgrade.

Otherwise, you're only choice is to attempt to repair your project manually. That could mean recreating all prefabs, adding all components again to all objects, assigning all inspector references, etc.