Hierarchical instanced static mesh component crashing after upgrade to 4.12

After project was upgraded to 4.12 opening a blueprint that contains Hierarchical Instanced Static Mesh component will result in a crash. From the log I this is the important part:

Assertion failed: InComponent->InstanceReorderTable.Num() == InComponent->PerInstanceSMData.Num() [File:D:\Build\++UE4+Release-4.12+Compile\Sync\Engine\Source\Runtime\Engine\Private\HierarchicalInstancedStaticMesh.cpp] [Line: 756] 

Removing the component before upgrade will fix the problem. I re-added the component and re-set the nodes exactly like they were and everything works now.

Hi, thanks for the bug report report. I’ve entered ticket UE-31702 to fix the issue. Is the content small enough to upload? An easy reproduction case would be very helpful if you have one.

Thanks

The content is quite big, but the blueprint is basically a crane that add/removes chain links when moving down/up.

Component settings are default except for selecting the link mesh and setting collision to nocollision.

If you can’t replicate the the bug, I’ll try to create a test project at some point when I have the time.

I have tried to reproduce this with a simple blueprint which adds an instance in its construction script, but it opened fine in 4.12.

Would you be able to upload a cut-down version of your 4.11 project we could reproduce it with?

gareth dot martin at epicgames dot com

Please include a link to this thread in the email.

Thanks!

Can you give me a email address? I need to give specific access, since the content is confidential.

Hi, I sent you the link. I cannot add the link unless I force everyone to register to OneDrive with the email given.

Crash will occur when opening the BP_AutoCrane

Thanks! I’ve received it and attached it to our internal bug report. I’ll take a look at it as soon as I can.

It’s so much easier to fix when I have a repro project :slight_smile:

Thanks very much I got a chance to look into it today and it should be fixed for 4.12.3!