Unity 5.6 & backward compatibility with Unity 5.1 -> 5.4

Unity Engine
1

Hi,
I want to report that Unity 5.6 break the project compatibility with Unity 5.1 - 5.4, if you create a project with Unity 5.1 → 5.4 and you open it with with Unity 5.6 you’ll never be able to open it again with the original Unity version.
I know that Unity don’t officially support the backward compatibility, but it always worked for all Unity 5.x versions (5.1 → 5.4), and even if some features from recent Unity version isn’t supported in older Unity version the project will not be broken and it was possible to open it again with any Unity 5.x.

I think Unity team should keep the project compatibility between all Unity 5.x versions, if you create a project with Unity 5.x and open it with Unity 5.6 it should not be broken and it should be possible to open it again with the original Unity 5.x.

In my case I needs to switch between Unity 5.1 (to build for BlackBerry 10) and the recent Unity 5.x releases (to build for the other platforms), all my project modifications are done in Unity 5.1, I just want to open the project in Unity 5.6 to build for the recently added platforms (without doing any modification to the project), but as soon as I open the project with Unity 5.6 it broke the compatibility with Unity 5.1 :frowning:

2

My solution to this problem is having two copies of the same project on my computer. Project folders named after which Unity version was used to open it, like “game_unity54” or “game_unity56”. I use version control to keep these projects in sync.

3

Maybe this is a workaround, but we need to be aware to not commit the project after opening it with Unity 5.6 otherwise the project will be broken…
I really don’t know why Unity team has chosen to broke the project backward compatibility with this latest Unity 5.6!
Also, the Asset Store publisher need to be aware about this issue, if they upgrade their asset to Unity 5.6 it will be unusable with any older Unity version!

4

Backwards compatibility is never promised between versions. That it worked between the older versions you mentioned was just a happy coincidence since we don’t make braking changes too often.

When you open a project made with an older version there is a Big warning dialog warning you about opening a project with a newer version.