[Bug]Pressing CTRL+Z in viewport

When I press CTRL+Z in a viewport of a character after changing something the engine freezes and I have to go to my task manager to end the task.

This also happens sometimes when pressing CTRL+Z in a blueprint.

Not sure if it has been reported yet, but it is quite annoying.

Hi MrGoatsy,

I’m not seeing this same behavior internally. Could you post your Dxdiag (System Specs)?

  • Windows: Go to the Start menu and type ‘dxdiag’ into the search bar. Open the file and then click ‘Save All Information’. Post that text file here.

  • Mac: Go to the Apple menu and click ‘About This Mac’.

Does it also freeze for you in a new project?


I also found another bug, in my project I launched it as a standalone game, I pressed CTRL+Z and I couldn’t even end the task via the task bar, I had to restart my whole PC in order for it to work again.

It freezes for me in every project I have started at random periods when pressing CTRL+Z, sometimes I can send a report which I sometimes do, but I am not sure they arrive, because when I click send & restart, it never restarts.

Can you try the new 4.9 release and see if you have the same issues? 4.8 didn’t officially support Windows 10, so that may be the issue.

Yes, I am going to download it tonight, because I have a 2 megabit Internet connection, I will let you know after I have tried it.

Hi MrGoatsy,

Have you had time to try this yet?

The issue is still there, if it happens again I will post the error I get after it crashes and asks me to send & restart.

These two bugs I mentioned before seem to be gone, but I did manage to find a nasty bug with blueprints, to replicate this go in any blueprint add a bunch of nodes, connect them together and compile, if no error press CTRL+Z a bunch of times and the engine will freeze.

Here is the error log I got after the engine closed:

We have this crash logged in our system but we haven’t been able to get a reproduction internally.

I added a large amount of nodes and repeatedly pressed Undo, but I couldn’t get your results. Could you post a screenshot so I have an idea of how many nodes you are creating?

Not that many, about 10 nodes.

Okay, we managed to get a repro but it’s not exactly using the same steps that you are. However, the call stack is the same so the fix should correct both issues. It’s logged as JIRA UE-20644 and our developers will be investigating it further.



Thanks, hope you guys figure it out.