Unreal engine source migration procedure


When moving to a new Unreal version, we need to make sure that all our changes make their way to the new engine to avoid breaking your project and keep features working as expected.

So what would be the best way to do that, the best approach would be to do the following, in our case suppose that we would like to upgrade from 4.XX to 4.XX+1.

Here the proposed steps :


  • Remove your current workspace

  • Create a fresh GitHub code drop

  • Do a three-way Diff between the different version 4.XX original(source) + 4.XX Modified + 4.XX+1 original (source) in the following order :

  • Detect changes between 4.XX original + 4.XX Modified

  • Detect changes between 4.XX original + 4.XX+1 original

  • Detect changes between 4.XX modified + 4.XX+1 original

  • Merge over any custom changes

  • Reconcile workspace


Note : the upgrade/diff should be performed in a fresh workspace that has not been compiled and don’t have Setup.bat executed otherwise you’ll be diffing with millions of temporary files


Once the code is setup and everything compiles, it is recommended to open the editor and fix any warning/errors that show up in the log.

The last step would be to re-save the packages so they upgraded to the new version by running the commandlet

-run=ResavePackages