4.27.1 destroyed my life!

4.27 updated yesterday to 4.27.1. Now I can’t open ANY of my projects, or rather they open then instantly crash on clicking any button. Graphics drivers all up to date. Just lost 6 weeks work for a client. Absolutely destroyed… Thanks Epic Games
I have also lost all my vault thumbnails.
Have tried opening projects as copies in UE5 and no maps are showing.
Datasmith plugin says there are no compatible engines!!!..ffs!!

Can’t you build 4.27 from source?

Hi Rectus
Thanks for the suggestion, but had already tried everything in the book… BUT:
Fixed…I had to download OLDER Nvidia drivers! So re-installed with old drivers and woohoo :slight_smile:
Nvidia and Epic should really talk to each other, but at least now I can rescue 6 weeks of work…a very stressful day!!


For anyone with similar problem and Nvidia RTX cards…457.09 drivers seems very stable now.

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Well, backup and a VCS software is your friend at these times. Usual advice:

  • pause Windows updates;
  • only use NVidia Studio drivers instead of Game Ready drivers;
  • unless if absolutely necessary migrate your project to a new release (if it has a show-stop bug in a previous release which prevents you from moving ahead);
  • each task, start a new branch on your VCS software, commit each task as it finishes;
  • backup after each task complete, just a smart backup software which can do fast incremental backups;

Life saved!

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I do only use the Studio drivers as I do a lot of CAD and design.
I stopped windows updates completely in win 10, but now on 11 need to find where it is…its a slightly different beast, but will get to it eventually.
As for VCS software, I will look into it… thanks for the advice…appreciated muchly


It’s not fair to them, Epic stated, that 2.47 will NOT BE compatible with UE5. That’s why we do not upgraded to it. It was even mentioned in the UE5 talk.

This is the exact problem I am having. Do I uninstall Nvidia graphics driver entirely before installing this particular one?

The nvidia installler will give you an option to do a clean install under Custom Installation (I think)

I wasn’t querying 5, 4.27 upgraded to 4.27.1, thats what gave me the issue. 5 works fine on its own.

This might be outdated too, somehwere later they said something along the lines, that the Early Access Versions of UE5 are/will not be able to convert 4.27 scenes, but the final version of UE5 will be able to convert them.
I am just not sure, where i read that, so take it with a grain of salt.

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To be honest, if you are not using any version control system (like git) it was just a matter of time. That’s a number one priority, not only to back up but also to branch your work and give yourself a possibility to rollback into a stable version.

Great you were able to fix the issue.


I tried to roll back to 4.27, but can’t find that option anywhere.
Once it upgraded to 4.72.1 I lost the ability to open 4.72 (unless I’m doing something stupid (won’t be the first time))
I don’t use Github…maybe I will look into it to see if its on there.
Thx for the advice anyway.

Look into Source control going forwards. Perforce or Git.

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Can you still create new projects with 4.27.1? New blank scenes, or do they crash too?

If you can open a completely new scene, then you can try to copy and paste all the stuff in the windows explorer from your damaged project into a new blank project (maybe bit by bit to check, if there is something specific corrupt in your projects).

Correct. It’s in the FAQ page of UE5:
UE5 Early Access is backward-compatible with Unreal Engine 4.26 and you will be able to open your 4.26 projects in UE5 Early Access. At the time of releasing Unreal Engine 4.27, projects generated in it won’t be compatible with Early Access; however, it is our intention that 4.27 projects will be compatible with the UE5 full release.

afaik. this just isn’t true. 4.27 is incompatible with UE5 EA because it was released after UE5 EA and none of the versions allow for projects to be converted to older versions.

But UE5 full release will be a newer so it should definitely be compatible.