World Partition Cell Stuck in Loading state

[NoaWinged]

Hi everyone,

I’m running into an issue with World Partition in UE 5.4. After I walk through a certain area, move far away, and then return, one of the runtime cells never finishes loading (it’s “stuck” on loading).

What I’ve observed:

• Using wp.Runtime.ToggleDrawRuntimeCellsDetails I can see the cell transitions to “loading” but then stays there:
  

• Increasing verbosity for LogLevelStreaming does not reveal any new info, only:

  LogLevelStreaming: Warning: Couldn't find ULevel object in package '/Game/XYZ/Maps/Worldmap_v2/_Generated_/DXMVN5BANAE0DI6VG1N6O5WCA'
  

• If I remove the entire data layer containing all interactive actors, the problem goes away. However, that layer contains hundreds of actors and manually isolating the culprit is very time-consuming.

• this issue only occurs in a packaged build - I can’t reproduce it in the Editor or when running in Standalone mode

Questions:

1. Are there any commands or profiling tools to pinpoint which actor or asset is blocking the cell load?
2. How can I catch or log more detailed loading errors for generated partition packages?
3. Has anyone encountered a similar issue or know of a UE5.4 bug/workaround?

Any guidance on debugging or isolating the problematic asset(s) would be greatly appreciated!

Thanks in advance,
Winged

[NoaWinged]

Update: Solution Found

I tracked it down by searching my entire project directory (using AgentRansack) for the stuck cell’s package key (DXMVN5BANAE0DI6VG1N6O5WCA).

That led me to the generated logs under Saved/Logs/WorldPartition/StreamingGeneration-Cook_*.log, which list every actor in each runtime chunk.

1. I pulled out the list of actors for the bad chunk.

2. I temporarily set bIsSpatiallyLoaded = false on all those actor classes to exclude them from streaming.
   

   

3. After some tests I could confirm that the stuck-cell error disappeared.

4. Using a binary-elimination approach (testing half the actors at a time), I isolated the single actor class that hung the load.

5. As a quick fix, I set that class to “Always Loaded” in my build, and the cell now loads every time.

I still need to figure out why that actor breaks streaming, but this approach got me to the root of the problem. I hope this approach saves you time (and spares you the hair-pulling) in the future!

PS If anyone has an even better way to find a bad actor in a World Partition cell, I’d love to hear it!

[volumetrix]

Great writeup on your investigation!

Did you figure out what about the actor was causing the issue in the first place?

[NoaWinged]

Unfortunately, nope . I just set this actor to Always Loaded and let it stay like this - I guess no project is perfect ^ ^