Undo in blueprints crashes a lot

With 4.9 I’ve become quite scared of undoing anything without saving beforehand. Sadly I am unable to reproduce most of crashes except for one.

  1. Create a blank project
  2. Add a Character or Player Controller blueprint
  3. Add a new function
  4. Click compile
  5. Press ctrl+z

Hi ,

I haven’t been able to reproduce any crash with these repro steps. Please reproduce crash following these steps, and copy information in Crash Reporter window, including Machine ID, and paste it here. Make sure you hit Send. Then logs from project’s \Saved\Logs folder and attach them here. Thanks!

Hi, I think I found problem, try these steps:

  1. Launch Unreal Engine 4.9.1
  2. Create a new project using a blueprint template (I used Side Scroller).
  3. Edit character blueprint and add a boolean variable.
  4. Compile.
  5. Ctrl+z.
  6. Crash.

Edit: Logs


I could reproduce this on 2 systems with binary version 4.9.1.
But it doesn’t seem to occur with current 4.9.2 git build so i guess it has already been fixed.

Crash report

Seems to be related to

HI everyone,

I attempted steps above but produced no crash while attempting them. Are there any other steps that can be added to reproduce this on my end? If you could, please follow 's steps above to send us callstack and logs. Additionally, please upload your dxdiag here so we can take a look.


Thank you for logs and dxdiag. Are you currently using beta AMD drivers for your GPU? If so, try rolling back to a released driver and see if that addresses error. If not, do you have an asset this has happened with I can look at?

Hi ,

This looks like it may have been addressed in 4.9.2 hotfix, can you update to 4.9.2 and see if this occurs for you still?

Hi, I updated to 4.9.2 and now It doesn’t crash so I think my problem is solved, but I don’t know if it is for OP.


Yes thank you, it seems to be stable now like in source version.

Hi ,

I’m happy to hear this is no longer occurring for you. I will mark this as answered for tracking purposes.