Correct Unity Version for Old Project

I am working on upgrading a project that is several years old for 64 bit iOS.

I downloaded the older version of Unity that was around at the time the game was last released hoping it was close enough to work on the project as a starting point. I have to remove several components that I know will not upgrade to Unity 5+.

The problem is that when I open the project in Unity 4 it goes through the process of importing all the assets. Once it is done several of the objects in the scene have lost their connection to the files they rely on.

For example several materials can’t find the shaders or textures they need.

It is my understanding that the import process only has to happen if the version of Unity you are using is different than the one the project was last opened in.

If that is the case is there a way for me to find out exactly which version of Unity this project was last opened in?

Usually the prompt that asks you to upgrade states the version of Unity the project was built in. But that might be a 5.x+ feature… not sure.

I figured it out. I opened the ProjectSettings.asset file in a hex editor because it was set to binary mode the last time the last dev saved it.

Not far from the top it lists the exact version of Unity that was used to edit it.