koobas.hobune.stream
Unity 5.5 downward compatibility
Hi Am I correct in assuming that once you open and save your project using 5.5 you will no longer be able to open in an earlier version without 'breaking' it? ie 5.5 is NOT downward compatible
Well, in general Unity always was kind of backwards compatible "to some degree". So usually you can simply open a newer project with an older version of Unity. Where things can break is "serialized data". That includes prefabs as well as scenes. In most cases they should load just fine. Even if you may used new components that didn't exist in the older Unity they usually just fail to load and can be removed after loading.
However there never has been any officially guaranteed backwards compatibility between any versions of Unity. That's why Unity warns you when you try to open a newer project with an older version.
In any case no matter if you upgrade to a newer version or downgrade to an older, always create a backup of the project if you fear loosing anything. Personally i have a lot test projects which i don't backup ever, but if one breaks i don't care ^^. Code is never lost and that's my main concern. I don't care much about scenes and prefabs.
Though since scenes and prefabs can be serialized as text the compatibility usually is high and in case of a complete break there's still a chance to fix it "by hand" since it's just text. That of course assumes that you have set the serialization setting to "force text".
So if you plan to downgrade a project you should:
Make sure you use text serialization in the project settings
Make sure you made a backup before you down grade.
Found unity would mess it up, remove names or even worse... But it is very easy to convert manually when the files are serialized as text.
So I wrote a small script that adds context menus to the files to convert them:
It replaces all GO serialized versions 'serializedVersion: 5' with 'serializedVersion: 4', which can be done manually in a text editor, too.
It shortens the GUIDs (16 in 5.3+ is too long for <5.3) when target version is below 5.3. This is tedious to do per hand, hence the script. It is not optimised and written quickly as I'm in a hurry to have it ready, but it works for the most part. Don't ask me why this works, but it does. Setting serializedVersions lower just prevents unity from messing with the files, which works, and the ids is the only critical part it has to fix.
Anyway, hope it helps anyone. It can be downloaded here: https://gist.github.com/Seneral/d88d2079ff17f77f2bd1775aadb8547b
It performs on text serialized files, so pelase remember to (atleast temporarilly) force text serialization!
Seneral
