Identical Content is cooked differently each time

Hi everyone,

We’re noticing a situation where we can create a release package, then immediately create a patch from the very same content and UE4 gives us a patch that is 1GB in size and contains all our maps, plus a smattering of other content. We don’t change any code, or contents or even open the editor. All we do is uncheck the ‘create a release build’, check the ‘Generate Patch’ checkbox and set it to use the release version we just created as the base.

It had been baffling us, so we cooked all our content, copied the cooked content into a safe place, then cooked the content again. Same settings both time, no changes to anything. If we compare the umap files in winmerge or something, we find that a few bytes or so have changed. The changes always seem to be near the top of the file, so might be some kind of header info?

We think this is why they are being added to our patches, as the unrealpak thinks the asset has been modified, and therefore includes it in the patch.

Is there any way we can inspect the contents/header information of the umap files which might give us a clue as to what is going on?

Thanks,

It seems to be that this is a serialization issue in the engine.

See here for further details on answerhub: