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Unity 2018.3 upgrade destroys all Prefab references in scene

Discussion in 'Editor & General Support' started by ShilohGames, May 5, 2019.

  1. ShilohGames

    ShilohGames

    Joined:
    Mar 24, 2014
    Posts:
    3,015
    I tried upgrading an existing project from Unity 2018.2.20f1 to Unity 2018.3.14f1. The upgrader trashes all of the prefabs in the scene. Every object in the scene that is connected to a prefab gets filled with missing references.

    I assume this is related to the changes to how prefabs are handled differently in 2018.3, but I also assumed Unity's upgrader could handle properly converting an exiting project. Is there anything special that I need to do to my project prior to upgrading it with Unity?
     
  2. ShilohGames

    ShilohGames

    Joined:
    Mar 24, 2014
    Posts:
    3,015
    I managed to find a solution to my own question. In my project, Unity 2018.3 was showing missing prefabs because it could not compile items in the package manager. In my case, Entities would not compile. I tried fixing this using the package manager UI, but without success.

    What finally worked for me was creating a new empty project through 2018.3, and then copying the Packages\manifest.json file from the new empty project into the my existing (old) project. Then I opened my old project in 2018.3 and manually re-added packages that I need, including Entities. After I did that, Unity re-compiled everything the prefabs in my scene were back to normal. That cleared up the missing references problem with the prefabs.

    So as odd as it sounds, Unity 2018.3 simply does not evaluate the prefabs references until after the compiler has run successfully.
     
    OwlBoy- likes this.
  3. OwlBoy-

    OwlBoy-

    Joined:
    Dec 11, 2015
    Posts:
    24
    Thanks, @ShilohGames

    I found the same thing happening upgrading VRChat projects from Unity 2017 to Unity 2018. I needed to remove a few incompatible scripts to get the project to reimport/update properly. Otherwise, I had broken prefabs all up and down my hierarchy.
     
    milox777 and ShilohGames like this.