Just spent an hour backing up my project and five hours waiting for it to upgrade it to the new version only to discover it broke my project. That’s a lot of development time I blew this weekend Thank god for back ups and older version downloads!
Just a rant while I download the version I was happily working with and a lesson learned: don’t update on the weekend!
How did it break your project? I haven’t updated to 5.1 yet
Just got a ton of errors that I didn’t have before and didn’t look to deeply into it. So I moved back. Just hated spending that much of my weekend waiting.
No offense against the OP (I hope you get your project sorted out in 5.1 eventually), but I recommend not replying to this thread. Let’s not have this post floating near the top of the page for the next 4 days.
EDIT: When I posted this, the thread’s original title was “Worst Upgrade Ever”, and the OP had just written that he had rage-quit after seeing some post-upgrade errors ‘without really looking into them.’ Since then it seems like things have turned around a bit, and the thread was renamed to something more useful to forum goers, so no hate intended. 
Yup. You have just discovered why big studios don’t upgrade engines mid project. There are always a ton of little things that need tweaking on each major version change. So unless you have time to deal with it, or you need new features, don’t upgrade. Wait until your current project is shipped, and upgrade then.
You can also install multiple versions of Unity if you want to run different projects on different versions.
I upgraded with a few fixable errors and the project on the burner at that time was suffering at 6FPS in 5.0.x when piped out to Syphon and then into a VJ app for projecting video on arena/nightclub screens. After a 3 hour import I recompiled once and stress tested it with the real world app it was being used with and it was running 10X faster at 60.2FPS.
I upgraded over the weekend (5.0.1 → 5.1.?). Was trivial.
Upgrading Inferno from U4 to U5 took about a week, but again, nothing major. I was generally pleased with the upgrade process. It went pretty well. Only thing that didnt work out was wheel colliders, but that turned out to be the values I was initializing with.
I dont see the point in rolling back between v5 releases. U5 is buggy. Needs teh fixes. Roll forward, fix problems, carry on with life.
I think the worst thing in Unity 5.1 is that there is no BEAST! No offense to developers but the new lightmapping system sucks. It has got a lot of bugs and takes forever to bake. BRING BACK BEAST!
Hello everyone!
Firstly, you can always report a bug/workflow issue/regression directly in the editor.
Help → Report a Bug.
And the more information you give us, the better! A repro project (Doesn’t have to be your WHOLE GAME, but a secluded scene (and assets) would be useful) can be attached to help our developers to have a better idea/clearer overview with what to fix in your project.
@drewradley : How did it break your project? You haven’t actually stated what happened…
Honestly, I didn’t look beyond seeing that the “clear” button didn’t remove the errors and that there were hundreds of them. By that time, I was annoyed with having wasted my entire Saturday afternoon trying to upgrade instead of developing and “rage quit”. I’ll try it again during the week while I’m at work and not actually trying to get something done on my project. I’ll do bug reports then as well, should they be bugs and not, say, user error as I suspect.
Wait, was this an update from 4.x to 5.x or from 5.0 to 5.1?
4.x to 5.x brings a lot of errors. But there is an auto updater that will fix most of them.
I noticed I got my scripts upgraded between 5.0 and 5.1… not sure why, guess they changed some API.
I would expect 4->5 to be troublesome, but less so minor updates.
Just from 5.0 to 5.1. I’m sure it’s user error as I was getting some weird errors before updating (like compile errors for some things like the UI Canvas Scaler that probably should never get errors). Backup works fine though.
Am i the only one who didn’t have a single problem or error when i upgraded to 5.0? 
It was so easy and everything kept working without making any changes. I guess i’m lucky 
Still need to upgrade to 5.1 though.
No. Most of us had no issues.
People just don’t often start rant threads with “Everything went fine, thanks guys”.
Yeah true, it’s like that saying: “quiet customer is an happy customer.”
I guess those who have problems stand out much more than those who don’t.
It does really help if you go into more detail about what exactly has gone wrong in your project, otherwise no one knows what to recommend. At this point I can only say to always check the release notes before updating to see what the changes are that could affect your project. http://unity3d.com/unity/whats-new/unity-5.1.1
•Changed thread title
But now you ‘dipped your toe’ in to 5.1 and saw the errors, you’re now faced with the fact that the longer you wait to update, the potentially more errors you’ll have to fix when you do switch. I couldn’t do that, I needed to switch.
I do intend to update and look more into what caused the problems and will follow up with anything I can’t fix myself. I was more expressing frustration than looking for help. I would have posted in the correct support forum had I been looking help and not just blowing off steam.
Thought I do appreciate all the encouragement from everyone here.
Has the issue been resolved? I’d hate to break my project, but need performance things that arrived in 5.1 and physics fixes. So I’d like to know if something similar to what happened to OP happened to someone else and if there was patch released that could fix similar errors.