WorldPartition causes random, unrecoverable crashes

First time around I would have put this down to a random glitch, but this is the second time my project has been put in an unrecoverable state after switching to WorldPartition. It’s really concerning because while it’s okay to have buggy or incomplete features, any feature that can literally destroy your entire project needs immediate attention.

The first time, I had force-deleted an element from a WorldPartitioned level, against the warnings, so I thought maybe it was my fault.

The second time was just a random crash, the engine was just sitting there in the background while I was working on something else.

In both cases, on subsequent loads, the engine immediately crashes on startup and it is impossible to get it to finish loading.

Assertion failed: ActorPtr.IsValid() [File:D:/build/++UE5/Sync/Engine/Source/Runtime/Engine/Private/WorldPartition/WorldPartitionActorDesc.cpp] [Line: 279]

The only way to fix this, that I’ve found, is to systematically delete folders in YourProject\Content_ExternalActors_\Levels\AffectedLevelName until it decides it wants to load again, and when I say “fix”, this means “but losing potentially a lot of work”.

Obviously since there’s hundreds of directories in there, it’s a massively time-consuming process.

For a bigger-budget studio you would implement a Perforce or other VCS. For smalller or solo devs, we don’t really have the resources to be doing that.

Unfortunately I’ve no idea specifically what actions cause this, so can’t provide any steps to reliably reproduce it. I think someone would need to have a go at catching the failed assertion at WorldPartitionActorDesc.cpp:279 and handling it more gracefully.

I’m familiar enough with software development that I can theorise how I’d fix it, but not enough so with C++ that I could provide a patch. Perhaps someone on the UE5 team or someone who is familiar with the WorldPartition code would be able to take a look?

I know I’m not the only one to have suffered this issue, but it’s hard to gauge how widespread it is, so it might just be a very edge case. Hoping desperately it can be fixed, because days of my life are being consumed restoring folders one by one until I find the “problematic” one!

I woke up this morning unable to load my project because of the same crash.
I’ve been working on this project for a few weeks but now it looks like my day is ruined and I haven’t even had my coffee yet. :frowning:

Just bumping to see if anyone figured out any other type of fix before i go in and start deleting stuff oe by one.

Also to note that I did start off the project with world partition enabled, but after having some other issues with it, I disabled it in the Project Settings but it looks like that doesn’t get rid of it. :confused: