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Editor hangs on specific Animation Blueprint asset (included)


Branch: Binary build from the Unreal Launcher

Build version: 4.9.2-2707645+++depot+UE4-Releases+4.9

Issue description:

Today I was playing with Animation Blueprint asset and was in constant edit->run-to-test cycle. After one of such edit iteration on Event Graph of that Animation Blueprint, I press Save and then rapidly Compile. That cause editor hang and constant increase of memory use by editor process. After a bit of waiting I kill the editor process via the Task Manager and try to reopen the project. Project was successfully loaded but editor hangs again right after loading with the same behavior: UI is not responsive in any way + constant grow of used memory. Suspecting that that Animation Blueprint asset become the cause of problem, I move it manually to another project and try loading this project. Project was successfully opened and no problem were observed. I was able to open that suspected Animation Blueprint and there are was compiler error reported due to missed Blend Space referenced by this Animation Blueprint. I delete this missed reference node from the graph, press Save, Compile and got exactly the same hang behavior as in original case. So the problem seems to be really in specific content of this asset after my last edit operation (added some nodes and reroute some pins).

Repro steps:

  1. Add asset from folder "version1" of attached archive to any project (by copying to project's content folder)

  2. Open project

  3. Open that suspected asset

  4. Fix compiler error by removing erroneous node from the graph

  5. Save

  6. Compile

  7. Editor should hang [Observable issue]


  1. Add asset from folder "version2" of attached archive to any project (by copying to project's content folder)

  2. Open project

  3. Editor should hang [Observable issue]

  4. If editor doesn't hang try open suspected asset, in this case editor should hang [Observable issue]

"version1" included in attached archive is the initial version of problematic asset

"version2" included in attached archive is the version of problematic asset opened and changed in another project (to fix the compiler error)

Product Version: UE 4.9
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asked Oct 08 '15 at 11:47 AM in Bug Reports

avatar image

Alexey Kryshen
33 1 2 6

avatar image Matt.Williams Oct 09 '15 at 05:00 PM

Hi Alexey,

When you send just the AnimBP, it has no link to any skeleton or animations. Could you make a blank project and migrate both the Version1 and Version2 AnimBP's to it? Use the Asset Actions>Migrate feature in the Content Browser right click menu. Then attach the project here.

It'd be great to get a repro for a memory leak as that has been something we've been struggling to find.

-Matt W.

EDIT: Also, thank you for being pretty thorough with your description.

avatar image Alexey Kryshen Oct 09 '15 at 07:24 PM

Hi, Matt

It is impossible to use Migrate operation on this particular asset because editor become unresponsive right after loading project with this asset, it just constantly consume memory and doesn't react on any input. The another problem is that minimal project I was able to make to reproduce the problem is about 20Mb, so I would be unable to attach that project to my post (there are restrict to ~5Mb of attachments AFAIK). But I got clean reproduce with simple steps you could do by yourself and all you will need are the same UE version I use and previously attached archive with problematic assets.

So, to reproduce the problem:

  1. Make new project with "Blueprint Third person" template, with no starter content

  2. Close the editor right after new project will be opened

  3. Copy problematic asset from the version1 folder of archive attached in my initial post into Content folder of that newly created project

  4. Open project again

  5. Try to open the problematic asset (UE4_Mannequin_Anim_Blueprint)

  6. Editor will complain that it could not find the skeleton for it. It Ok, just press "Yes" to replace skeleton reference

  7. Select UE4_Mannequin_Skeleton in opened dialog and apply it to retarget

  8. After retargeting will be complete (notification message), open problematic asset. Now it should be opened but will signal about compiler errors (via the icon on Compile button).

  9. Press Compile button to get explicit list of these error

  10. Remove two nodes it complain about (these are: Play and Blendspace player)

  11. Press Compile button again and you are done. Editor will hang at this moment and will start consume memory constantly [Observable issue].

I try it several times and it 100% reproducible on my machine with these steps. Please let me know if you was able to reproduce the problem with these steps. Otherwise I will provide you with my test project somehow.

Best regards, Alexey

avatar image Alexey Kryshen Oct 09 '15 at 07:39 PM

Hi, Matt

It seems that problem with that asset is in execution loop between two nodes I have erroneously create (ooops :) )

alt text

If I break this loop by removing execution link from "Print string" to "Set variable" then it compiled just right and issue is gone (you can do that before step 11th described in my previous comment).

Hope this unintended test-case will be helpful for your team.

Best regards, Alexey

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1 answer: sort voted first

Hey Alexey,

Apologies for the late reply. I have entered UE-22655 into our system after reproducing the issue. Thanks for reporting this...and watch out for those endless loops!!

-Matt W.

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answered Oct 27 '15 at 06:29 PM

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