UE 5.7 Control Rig Creation Crash Triggered by “skel” Prefix in Skeletal Mesh Name

Development Character & Animation
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1

When generating a Control Rig from a Skeletal Mesh that contains “skel” in its name—or uses it as a prefix (i.e. skel_test)—Unreal Engine crashes.

The crash occurs both when using the native Create Control Rig button in the editor and when calling the Create Control Rig Blueprint function node.

This issue was observed in Unreal Engine 5.7; other versions have not been tested.

2

Steps to Reproduce
name a skeletal mesh uasset `skel` or name it with a `skel_` prefix, i.e. ‘skel_rig’, ‘skel_test’

right click on the skeletal mesh -> create -> control rig

Unreal Engine Editor will crash and close. with the pop up error ‘Fatal error!’

3

Hey there,

Yes this is the case, I need to chat with the dev who implemented this change to double check some knockon effects before I log a bug, but if you’d like you can remove:

// Skip SKEL classes.
if (InObj->GetName().StartsWith(TEXT("SKEL_")) || InObj->GetName().StartsWith(TEXT("Default__SKEL_")))
{
	return;
}

from URigVMBlueprintGeneratedClass::PostInitInstance

and that should get you moving again.

Dustin

4

Thank you Dustin, we’ll try that out!

Is there a list of prefixes/suffixes or keywords that should be avoided in asset names we can reference for the future?

5

No, this looks to be the only one. This check has been in for over a year, and you are the first ones to hit it!

Dustin

6

Hey there,

You can safely delete it; you shouldn’t run into any issues. This will be removed in a future refactor of some of the control rig instantiation, and so there isn’t a need to log a bug against it.

7

another weird behavior that I’ve found that is related to this bug is if I take any control rig uasset (CR_characterName.uasset) and rename it to have skel prefix (skel_characterName), it will break the control rig.

I took Unreal’s native mannequin control rig (CR_Mannequin_body), duplicate it and rename it (skel_CR_Mannequin_body), double click to open control rig editor and you will see the controllers disappear and the rig doesn’t move correctly anymore.

8

confirming that this change worked! Thank you so much!