I “upgraded” my ue4.23 project to ue5 a couple months ago.
All my assets, but particularly the blueprints, have become unopenable.
Can I downgrade the project or at least port my assets to a ue4 project so I can make them (mostly) working again?
Also I don’t think this is the right forum for this. So feel free to move this thread to the right one.
Thank you.
In a world, no. I’m afraid.
Do you have a backup from before you migrated?
Hi KeyC0de,
I’ve never done this myself, but I do know about a community article that explains how this might be possible.
5.1 preview should be releasing soonish, chances are low it will fix/change anything, but it’s worth trying to open your assets in that version.
Until now, nope. You have to fix it manually, tracking all issues on BP, compiling, and searching.
And that’s the reason we have to create multiple copies of our projects. If possible, buy an external HDD only for your game projects (despite my projects having pretty large files and I create multiple projects in a small 2TB external HDD). A simple 1 TB HDD will be enough for your game projects, I bet. Unfortunately, it means more money to spend.
Thanks for everybody’s answers.
You mean that v5.1 hopes to allow ue4 project files to be supported?
Hi again,
Sorry for any confusion. Opening files from any versions of UE4 in UE 5.0 or 5.1 is supported, but when blueprint nodes change / are deprecated there can be problems.
I think best path forward would be to open your 4.23 project in 4.26 or 4.27, and ensure all of your blueprints are compiling before using UE5.
Actually my blueprints were not deleted, I found that they were put in “Saved” folders.
So I meticulously restored them back to their original folders in “Content” and removed the _Auto# suffix they had.
Now opening some of them work, but others cause a crash saying: “epic games unreal engine corrupt data found please verify your installation”.
So I’ll try your suggestion tomorrow, I’ll download and build the latest
preUE5 source version and try to open them there and we’ll see what happens.
Thanks.
Ok actually I did it today.
So more files open up on ue4 .27 but some do not and they crash with that error in my previous message.
So apparently I have some nodes there that are not supported?
Is there an automated tool or something that can go through all those uasset files find unsupported elements and remove them or something?
Thank you.
Glad to hear you made some progress,
I’m not aware of any ‘cleanup’ tool. (In my experience UE has been good about marking nodes as ‘deprecated’)
If you’re still able to open up these BPs in an older version, you will be able to copy+paste blueprint logic. (Probably best to do it into an intermediate project first for when you run into the crashy bits)
Good luck!
No, I can’t open those files in any version.
I tried opening them in the version I created them which is 4.23, no deal.
Then I tried opening them to the version you suggested 4.27 - still nothing.
I’m gonna need some sort of utility that gets rid of those invalid nodes or something so that I can open those blueprints, otherwise they’re gone for good.
Cheers.
You can now using my plugin (https://www.unrealengine.com/marketplace/en-US/product/asset-downgrader) It downgrades assets to 4.27, with certain limitations (for now). Let me know if it works for you. If not, contact me and I can do more research/fix it.
Looks promising.
I’ll test it and report back.
If it works, you’re promoted to king of the world.
PS: I hope it works for blueprints too.
However, I want to downgrade to version 24.3 and it doesn’t look like that’s possible. 
Actually, my problem is that I want to open 1 blueprint in particular.
It crashes the editor upon attempting to open it.
The problem occurred when I upgraded my project from 4.24 source version to 5.3 source version and foolishly not making a backup.
I wish there was a way to figure out what was the offending part of that blueprint and somehow was able to extract it.
I’m not 100% sure, but I believe the reason it crashes is because I used a custom plugin in the blueprint that was not available in the new engine or something like that.
That’s why I don’t think your downgrade plugin is gonna work either (after reading the requirements & details).
I wish there was a way for me to somehow debug the blueprint somehow to see what’s going on with it.