Converted Project from 4.12 Crashes On Startup In 4.17

I have a project that was being made in version 4.12, and I recently decided to update it to 4.17. So, I did what the project conversion process, like normal. However, despite converting it, it crashes on starting up the project. I’ve attempted a few things: Verifying my version of UE4 4.12 and 4.17, repeating the process again and also copying the actual project folder directly and converting in place, and still the same thing. I don’t know what it could be, I can’t seem to find a way to get a log to even take a look at might be the problem. Any ideas?

you should post crash log as well. That would hold clues to what might possibly be wrong with conversion. Someone might be able to help better then.

Here is the summary information, hopefully, it can say what the problem is.

Assertion failed: 0 [File:D:\Build\++UE4+Release-4.17+Compile\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\Linker.cpp] [Line: 60] Package level compression cannot be used with the async io scheme.

UE4Editor_Core!FDebug::AssertFailed() [d:\build\++ue4+release-4.17+compile\sync\engine\source\runtime\core\private\misc\assertionmacros.cpp:349]
UE4Editor_CoreUObject!FCompressedChunk::FCompressedChunk() [d:\build\++ue4+release-4.17+compile\sync\engine\source\runtime\coreuobject\private\uobject\linker.cpp:61]
UE4Editor_CoreUObject!operator<<() [d:\build\++ue4+release-4.17+compile\sync\engine\source\runtime\core\public\containers\array.h:1076]
UE4Editor_CoreUObject!operator<<() [d:\build\++ue4+release-4.17+compile\sync\engine\source\runtime\coreuobject\private\uobject\packagefilesummary.cpp:254]
UE4Editor_AssetRegistry!FPackageReader::OpenPackageFile() [d:\build\++ue4+release-4.17+compile\sync\engine\source\runtime\assetregistry\private\packagereader.cpp:65]
UE4Editor_AssetRegistry!FAssetDataGatherer::ReadAssetFile() [d:\build\++ue4+release-4.17+compile\sync\engine\source\runtime\assetregistry\private\assetdatagatherer.cpp:836]
UE4Editor_AssetRegistry!FAssetDataGatherer::Run() [d:\build\++ue4+release-4.17+compile\sync\engine\source\runtime\assetregistry\private\assetdatagatherer.cpp:597]
UE4Editor_Core!FRunnableThreadWin::Run() [d:\build\++ue4+release-4.17+compile\sync\engine\source\runtime\core\private\windows\windowsrunnablethread.cpp:76]

I have the same problem project conversion failed and as result it crashes.

I have the same problem project conversion failed and crashes

To fix the problem, it’s better to create a clean project and export everything there. This problem is solved, but it takes a very long time to make everything work as it should.

So if I do that, will it all work as it should? Or will I need to do some fix ups?

Of course it all depends on what kind of error you have. You need to delete project folders “Intermediate, Saved”, also delete the following file from config folder DefaultEngine.ini or replace from default empty project.

I did end up finding the problem, it was an asset that was causing it crash. I deleted it and it works fine now.