revert/downgrade project from 4.11 to 4.10

Hello all,

I made the terrible mistake by updating my project to the latest version of Unreal Engine (4.11).
this caused my problem: I can’t open my unreal project because the plugins installed (Substance plugin and Rama’s Vertex editor plugin) aren’t up to date.
I haven’t been able to open the project in the editor itself because before it loads completely, it stops with an message that victoryEdPlugin (Ramas vertex editor) can’t let the editor open.

I hope there is a way to revert/downgrade my project back to 4.10, because I really need to be able to build my game for an interview for a school I applied to.

with kind regards,


There’s no way to use projects made with a newer version of the engine with old versions, due to the significant changes that are made to the engine. You should be able to open the project though if you remove those plugins, I would think.

yes there is, I just found out in a post in the same section (general discussion) that when you open UE4 and browse for the .uproject file of the project you are working on. and rightclick on that file, there is an option called “switch unreal version” in there you can revert to an older version.

dont know if this also works if you have edited your project with the newer version of the editor btw.

manny thanks to Erik Bye for the answer

Uh… so, here’s a problem. When you have a uasset in a version of the game engine, it’s internal binary gets serialized with the engine versions it is compatible with. Usually, a uasset is forwards compatible, but generally not backwards compatible. Therefore, if you create an asset in 4.10, it will open up just fine in 4.11. The engine won’t open the file to write any changes to it. However, if you create an asset in 4.11 and want to go down to 4.10, you very likely will not be able to (depending on what features in 4.11 you used with the asset).

**Pro tip: **BEFORE you start working with a project in an updated version of the engine, do a FULL BACKUP onto an external hard drive. If you need a ‘go back’, as you do now, you have a very painless recourse.

If necessary as a last resort, can you open two different versions of the editor…
Then use copy / paste or CTRL-C / CTRL-V to extract certain parts…???
(You could get away with this in UDK at times, but UE4 is a whole other beast :slight_smile: )

Yes, you CAN open two instances of the editor. You don’t necessarily want to just copy/paste assets from one version to another, you’d ideally want to use the asset migration tool. This will capture all of the dependencies of your asset and migrate them as well (ie, an animated character will have animation sequences, animation blueprints, textures, materials, normal maps, etc). Each UASSET file will have the compatible engine versions serialized into its binary, usually in the header section of the file. Keep in mind that your project is more than just the content as well, you’ll want to capture your config files (to get things like input actions and key bindings).

If you didn’t make any changes to any uasset files in 4.11, you can pretty much just open your Content directory (in explorer) in your 4.11 project and copy/paste that into a content directory in 4.10.4.

No, I meant if can you open two different releases of the editor simultaneously i.e. 4.10 and 4.11 running at the same time…
This wasn’t a problem in UDK, but UE4 is more expansive, there may be registry-key / DLL overlap demons waiting…
Also memory: 4.10 leaked badly, jumped from 2-10GB and also drained video-memory, the latter causing instant crashing in all sessions!

Yeah copy / paste is a bad idea for UE4, that’s why I wrote the words last resort above. Its an unfortunate habit spilling over from UDK.
But it is handy sometimes when you want to review assets from a 3rd party project, but don’t want to contaminate the master project.

After all the other suggestions are explored, if you’re still locked out of the editor, you can try programming hacks like renaming Rama’s DLL or the other dependencies and see if that allows you to progress further into the editor. If Rama’s DLL is self-contained you could try getting hold of it directly (he updated some yesterday!) Microsoft Depends.exe utility may help here too…

Yes, you can do this and I’ve done it many times. They’re still instances of the same program / application.
Keep in mind that when you load any software which uses a DLL, the DLL’s get pushed into shared memory. These are accessible by any instance of the program.

So… if the very first instance of an application consumes 100mb of memory and 50mb of that is DLL loading, then a second instance would only add another 50mb to main memory because the DLL’s from the first instance are already loaded. This is taken care of for us by the operating system…

So, when I say “instance”, I don’t make a distinction between engine version numbers because it really doesn’t matter that much.

As for the memory leaks, I’ve run into these problems with UE4. I have 24Gb of main memory on my machine and when nothing is running, I sit around 2gb of usage. When I load UE4 and my project, I sit around 6-8gb. However, there are some things which will cause UE4 to allocate a ridiculous amount of memory (like, 105939459gb) which will cause an instant spike of my available physical memory usage, cause the OS to start paging out to the page file as fast as it can so that it can satisfy the malloc request, and because the OS is blocking on the page file request, the whole computer freezes and I have to reboot. These funky malloc requests generally happen when a uasset is corrupted (which can happen between engine versions) or when you have an infinite loop somewhere. I wish there was some internal engine logic that says, “hey, this malloc request is way crazy! we will crash the engine or abort with an assert before we freeze the computer.”

Good to know cheers!
(Wasn’t sure if 3rd party plugins could cause problems.)

Do you get any out of Video Memory errors?
(Instant Editor crash without warning, all sessions)

No, the only video errors I’ve gotten are complete video card crashes (all screens go black until reboot). These were caused by using a Vive with bad drivers from NVidia. It took me a bit of time to isolate the problem down to the drivers.

Thank you for making clear how it works, this is definitely going to help me in the future, but also a lot of people with the same problem.