Running Unity 2017.3.1f1. Looking to upgrade to 2018.2. Is this a one-way upgrade?

Do projects get permanently upgraded to the latest version of Unity? Does Unity have a history of breaking large projects with major version upgrades?

Edit: Maybe I am getting ahead of myself... the new features look awesome, but I will likely wait for a stable release

 

Yes. Yes. Always make backups before upgrading and never upgrade unless absolutely necessary.

 

Yeah nevermind... I just got excited reading the patch notes

 

With proper version control, nothing is one way. But be prepared to squash a few bugs along the way.

 

Upgrades are always "one way".

New versions of software often understand the formats from older versions so they can still load the data, then it gets re-saved in the new format. That works because the new version is aware of both the old and new formats.

However, old versions of software can't be aware of formats that didn't exist when they were created. So any differences just make the data unreadable to old versions.

 

True. But Unity seldom changes the format. While its not recommended or supported, its typically possible to load a project created in a newer version of Unity in an older one. I do it quite frequently when I am too lazy to download the specific patch someone else built a project in.

 

True, thanks to this stuff often ends up being compatible even though it's officially not, as long as you're not using the things that happen to have changed. The larger a project gets, though, the more likely you are to be using stuff that got changed. In particular, if you upgrade to get access to new features...

Also true that if you're using version control you can always roll back to pre-upgrade, and you might even be able to merge in post-upgrade changes. Unity just can't do it for you.

 

In the case of 2018.2 formats did change. If you downgrade back to 2018.1 or earlier stuff will break.

I saw missing prefabs in the scene, no idea what caused that. I also saw prefabs with rigidbodies become unable to drag them into a scene.

 

Why downgrade? The way you do it is to ensure a stable upgrade in a branch, this can take months in worst case. During this time you pull in the changes from Dev branch and make sure the upgrade branch is in sync with the development branch. When the upgrade branch us utabke and tested you can merge in the upgrade branch in dev

 

Because most people does not upgrade this way. They just open the sole project in the new version even without proper backup.

 

That's a one-way street to a distaser. My way is the correct way

 

When trying out beta's I often just take the route of upgrade, then immediately downgrade and look at my SCM to see what files got changed. Then revert any changes and either stick with what I'm on or upgrade again. If formats didn't change and there weren't widespread api updates, then a second branch isn't really necessary.

 

Says the dev who just created a thread about performance degradation in newer editors and SteamVR disconnects.

 

What does that have todo with anything, it's a performance regression going on in unity editor

 

I do the same for none major updates like going from 2017.4.5 to 2017.4.6

Edit: well I don't downgrade just check which files that changed

 

That is always the best way. On occasion if it is just for some quick testing or peeking to see what happens, I'll just dupe the project in the finder and check it out. Were I using Git, I would be more inclined to just branch.

 

Because of the time rebuilding library I always have 3 local copy's of the repo

It takes alooooot of disk