Backwards compatibility of Blueprints (uasset hidden when moving back to 4.4)

I was working on Blueprints in 4.5 (migrated these to another project which was 4.4) and the assets no longer show up when moving back to 4.4 I cannot recompile them either simply because they aren’t available in the Content Browser anymore.

I assume that what you are describing would be forward compatibility. Using BluePrints from a higher version in a lower one could break them, they are serialized and the size of the properties is very important. I had the same problem moving a BP from 4…4 to 4.3, the issue was that in 4.4 one of the parent code classes had a new property, a user defined struct in my case. The engine told me that the code is incomplete (check your log) and they never loaded. To fix the issue I just got rid of the code that prevents the assets from loading and commented a whole bunch of checks (you will have lots of crashes until you get it working!), and change some serialization to null or default values by hand.

I guess there is no easy way for you to use you BP in a lower version automatically, you can still copy&past the BP code over and recreate it in 4.3, this was my first attempt too but it took longer then fixing the serialization for my classes.


Thanks Moss, I did mean Forward compatibility indeed I suppose :slight_smile: I might just have to copy/paste over the content but I’ll check the log output first and see if anything can help me out there.

I’ll leave the question option since this still requires some usability attention from Epic.

Hi Tom,

Forward Compatibility is not generally supported by the editor, although some functionality in this area maybe added in the future.

Below is a forum post where Daniel Vogel briefly talks about this.

At the moment the only aspect that is supported in this fashion is material asset references and material overrides on sprites and flipbook assets. This was part of the Paper2D update.

I just found a Feature Request for this feature in our system that is currently being investigated by our developers. It stems from one of your previous questions about moving uassets.

Thanks TJ, it would be very helpful for people sharing uassets to display this properly to the user though. I’ve had multiple instances where people came to my asking me why the content wouldn’t show up and no notification or error is displayed. I can make a new answerhub entry for that as request if required.