Can't open project. Child actor issue?

zknet · March 28, 2016, 6:08pm

EDIT:

There’s more details below, but I want to summarize.

I have a couple of blueprints that are preventing me from opening my project. There’s nothing interesting in either blueprint. I was able to narrow down the problem for one of them: the project will stop opening if I use this blueprint actor in a child actor component. I’m not sure if that’s the root cause, but that’s as close as I’ve been able to get so far. (FYI, the other problem blueprint is not used in a child actor component. So, lots of uknowns still going on.)

Unfortunately, I don’t have any workarounds for this. I’ve tried lots of different things, but no luck.

ORIGINAL:

I have a binary copy of UE4 and my C++ project keeps getting stuck at 72% when I try to open it.

Here’s what I’ve tried:

Deleting transient project files (build, intermediate, etc)
Deleting DDC
Verify UE4 installation
Tried 4.11
Replacing blueprint asset files with an older version

Sadly, it’s the last one that worked. If I replace two of my blueprints with versions from last week then I can open my project. I’d rather not roll them back since I’ve done a lot of work in them over the past couple of days (and I can’t even look at them to reference them).

Is there anything else I can try?

Thanks,

PS: I was able to load up an earlier version of a blueprint and reimplement my changes. Once I made my changes, I was unable to open up the project again. So, there’s something about my blueprint that is causing it to not be able to load… although, I couldn’t even guess what it could be since I’m not doing anything interesting with that blueprint.

PPS: I narrowed it down to two blueprints that cause this issue. Neither of them are particularly interesting. Hoping that my existing blueprints were corrupted (or something), I reimplemented all my changes in one of those blueprints. Once it was brought back up to date, I wasn’t able to open the project again. So, not corruption. It’s definitely something in the blueprint. I’m trying to narrow down the exact cause, but it’s proving to be super difficult to track down. I’m really not doing anything interesting here, so I’m really stuck. The only thing I have left is just to arbitrarily rewrite this area and hope I don’t accidentally do the same thing again. (Which it is what I’ve been trying, but to no avail.)

PPPS: Here’s where the logging dies:

[2016.03.28-17.51.27:454][  0]LogTargetPlatformManager:Display: Building Assets For Windows
[2016.03.28-17.51.27:516][  0]LogDerivedDataCache:Display: Max Cache Size: 512 MB
[2016.03.28-17.51.27:546][  0]LogDerivedDataCache: Loaded boot cache 0.03s 38MB C:/Users/Zachariah/AppData/Local/UnrealEngine/4.10/DerivedDataCache/Boot.ddc.
[2016.03.28-17.51.27:546][  0]LogDerivedDataCache:Display: Loaded Boot cache: C:/Users/Zachariah/AppData/Local/UnrealEngine/4.10/DerivedDataCache/Boot.ddc
[2016.03.28-17.51.27:546][  0]LogDerivedDataCache: FDerivedDataBackendGraph:  Pak pak cache file ../../../../../../Code/BrightWorld/src/DerivedDataCache/DDC.ddp not found, will not use a pak cache.
[2016.03.28-17.51.27:546][  0]LogDerivedDataCache: Unable to find inner node Pak for hierarchical cache Hierarchy.
[2016.03.28-17.51.27:546][  0]LogDerivedDataCache: FDerivedDataBackendGraph:  CompressedPak pak cache file ../../../../../../Code/BrightWorld/src/DerivedDataCache/Compressed.ddp not found, will not use a pak cache.
[2016.03.28-17.51.27:546][  0]LogDerivedDataCache: Unable to find inner node CompressedPak for hierarchical cache Hierarchy.
[2016.03.28-17.51.27:592][  0]LogDerivedDataCache:Display: Pak cache opened for reading ../../../Engine/DerivedDataCache/Compressed.ddp.
[2016.03.28-17.51.27:604][  0]LogDerivedDataCache: Using Local data cache path C:/Users/Zachariah/AppData/Local/UnrealEngine/Common/DerivedDataCache: Writable
[2016.03.28-17.51.27:730][  0]LogCollisionProfil

anonymous_user_2b03d27c · March 29, 2016, 2:49pm

Hey -

It sounds like whatever changes you’re making to your blueprint are preventing the project from opening. Are you receiving a crash reporter window when trying to open the project? If so could you post the full callstack from the crash reporter? Also, could you explain exactly what you’re doing when the blueprints and at what point in the blueprint development the project stops opening?

Cheers

zknet · March 29, 2016, 4:29pm

Hi ,

Thanks for the response. Unfortunately there’s no crash occurring when I try to open the project. It just hangs when it reaches 72%.

I have not had any luck narrowing down the root cause. Right now, I can cause it to happen in a number of different ways. Add a particular type (HUD in one case) of variable to a blueprint; add an interface to a blueprint; change the actor used in a child actor component; etc. Which leads me to believe that the root cause is deeper and less obvious.

I did try to make a repro using all of the elements that seemed to cause the problem, but no luck.

I know I’m not giving you much to work with, but it’s one of those types of problems.

Thanks,

anonymous_user_2b03d27c · March 29, 2016, 6:15pm

If you’re able to find something that will routinely cause the issue (eg. adding a specific type of variable to a specific blueprint), can you post a copy of your project and state the steps that lead to the lockup.

zknet · March 29, 2016, 7:49pm

Here’s an easy one:

Open Content/Blueprints/Players/InventoryUI.uasset
Add a new variable named ‘HUD’ and make it type ‘PlayerHUD’.
Close project

Next time you open the project, it should get stuck at 72%.

Here’s the project

Thanks again!

zknet · April 1, 2016, 4:54pm

Hi ,

I was just wondering if you’ve had a chance to look at my project yet?

Thanks,

(I just realized I didn’t properly reply to your comment so you might not have seen it… oops.)

anonymous_user_2b03d27c · April 7, 2016, 7:41pm

Hey -

Sorry for the delayed response. I tested the project you sent and saw the loading issue. I submitted a report (UE-29204) for further investigation.

Cheers

Grogger · May 4, 2016, 2:22pm

Hi ,

Has there been any progress on this?
I’m running into the same problem, where the project stops loading at 72% and the process isn’t using up any CPU, after upgrading from 4.9 to both 4.10 and 4.11.

Unfortunately, I don’t know which files are affecting it (I’ve tried with revisions that are months back and have the same issue), but if there was progress on it, I could use the hint!

EDIT: Found it!

We’ve managed to find the offending code. It’s a few lines of code that were added a long time ago (works in 4.8 and 4.9):

static ConstructorHelpers::FObjectFinder<UBlueprint> defaultData(TEXT("Blueprint'/Game/Data/BP_UniverseGameData_Core.BP_UniverseGameData_Core'"));
	if (defaultData.Object && defaultData.Object->GeneratedClass)
	{
		LocalUniverseGameData = NewObject<UUniverseGameData>(this, TEXT("LocalUniverseGameData"), RF_NoFlags, defaultData.Object->GeneratedClass->GetDefaultObject(), true);
	}

This was placed in a constructor of another class. Commenting it out allows us to get passed the 72% and launch the editor.

anonymous_user_2b03d27c · May 4, 2016, 7:41pm

Hey Grogger-

We are still looking into this and don’t have a time frame for when a fix will be implemented. One way to find which files may be causing the problem would be to remove the Content folder from the project and then slowly reintroduce folders/assets from the Content folder back into the project until the error occurs again.