Why is there a crash on project migration from 4.6 to 4.7

I’m migrating a project from 4.6.1 to 4.7.6 and the project crashes on startup in 4.7.6. The offending asset seems to be a player controller:

Assertion failed: BlueprintObj->GeneratedClass [File:D:\BuildFarm\buildmachine_++depot+UE4-Releases+4.7\Engine\Source\Editor\UnrealEd\Private\Kismet2\Kismet2.cpp] [Line: 896]
Invalid generated class for ArchPC

any thoughts on a workaround? I’ve tried deleting the asset to break any dependencies, but that doesn’t work.

Hi paradoc,

What steps did you take to migrate the project from 4.6 to 4.7? Does this occur with a blank project created in 4.6 that is then migrated to 4.7?

I’ve only been able to reproduce this problem with this one particular project, but it’s 100%. Blank projects seem fine and i’ve migrated other projects ok as well. A wild guess, but in previous projects i’ve had issues with event dispatchers in the player controller, so usually created specific event dispatcher actors. In this project, I continued to use dispatchers in the player controller and wonder if that’s creating the issue. In any case, the PC’s are not too complex, so ultimately will redirect everything and delete the offending asset. When i get a chance to do this, i will follow up with any additional pertinent info.

ok, so i kept the original PC that was causing the problem in the project, but deleted the dispatchers and any references to them, cleared most of the graph, and was able to migrate this time without any problems.