Why is the version compatibility so strict?

Development Getting Started & Setup
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1

Fairly new to UE and been playing around with some of the tutorials from the learning area, and various marketplace projects / samples etc. I’m curious why the version compatibility is so strict? Lots of assets / tutorials seem to use slightly different versions (4.25-4.26, then something else is 5.1-5.2, something else 5.0 only etc…). With no option to open or convert to other versions without downloading the full engine for each version.

At this point my HDD is like 150GB just different versions of the engine :joy:. Is there really that much backwards incompatibility, even from things like 5.2 to 5.0? Why is it so strict? Any tricks I’m missing here or am I stuck just having to download the right version for every tutorial / asset I want to try?

Thanks!

2

You can right click a .uproject file and select Switch Engine Version.

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This will open a window with a dropdown to select the version you want from all the installed engine versions.

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:warning: Opening projects in different engine versions other than one the project was last edited in might result in loss of data or compatibility errors. It’s recommended to make a copy of the project before switching engine versions to avoid any loss of data.

3

Depends on what it is.

U asset files are blobs of stuff - usually byte - and are signed with the engine version.

You could manually hex edit the engine version and then use the file in whatever engine - provided the asset doesn’t contain something the engine changed.

Its basically a security measure to prevent crashes when they do suff like change what a node is called between engine versions.

90% of the time, if you throw the uasset in any engine, it will just work, if you save it it will obviously update.
The times it doesnt the engine will crash.

  • and if this isnt true for everyone, then I added something to do this in my custom engine build…
4

It is because of C++ code plugins/projects. And epic thinks it is better to be safe than sorry, so they made strict versioning for everything.

C++ plugin made for different binaries will not work because all pointers go derp. Other plugins/projects should be mostly fine.

And you can force opening project with different version of engine, but if it does not work its your fault, not authors of project.

5

150GB is nothing. For those who get by without needing Terabytes for Unreal Engine, please share your secrets. :stuck_out_tongue_winking_eye: See this thread below for example. Especially as it still makes sense to work with 4.27 & UE5 for now too, as there’s lots of subtle implications if you don’t. :rage: Too many details to go into here, but for now Physics / BP Nativization / Editor stability for starters.

Plus there’s also managing assets and projects. You’re looking at having to have many TB’s to hold all the different backup versions of projects, different engine versions and different marketplace packs to fit all the different engine versions. This all adds up. Especially when you factor in DDC storage too, across all the different engine versions. :wink: Or you can always stick to just one engine version, the latest and greatest, but that can mean lots of other ‘gotchas’. :rofl: