sierra full screen bug

I had this problem when updating to Sierra, even after the 10.12.1 update. Unlike others, it wasn't just Chrome, it was anything trying to go full screen. While the "create a new user account" thing worked, it wasn't ideal because who wants to start from scratch. Here's what I did to get this to stop. It's not quite perfect, but it's better than rebuilding my user account from scratch:

1. Create a new temporary user and make sure they have administrator privileges. ( OS X Yosemite: Set up users on your Mac )
2. Log out of the main account and log into the temporary account.
3. From the temp account, change the user name and the home folder name of to the main account. (I just added 'old' to the names.) Change the OS X user account name and home folder name on your Mac - Apple Support
4. Log out of the temp account and into the 'old' user account. It should like you remember, but it won't launch any previously open applications. Some of my accessibility settings were reset like "Reduce Transparency" but virtually everything else came through. Going full screen doesn't crash the system.
5. You can go ahead and keep using this account if you want, or you can change the names back by logging out, logging in the temp admin account, and changing the username and home folder name back in step 3.
6. When you're done, you can delete the temp account under System Preferences-> Users and Groups

I hope this works for someone, and maybe helps Apple get closer to a fix.

i have same problem. Any solutions?

Have any of those of you working on this with Apple received a reply? I can confirm this persists with 10.12.1

I spent a few hours on support with them last week, and we couldn't come up with a solution.

Resetting NVRAM/PRAM did not work.

Setting up a new account works, but I'd rather not migrate everything.

Safe mode boot works.

For fun I created a new user, migrated everything from the older user to the new one, including ultimately switching over the UID, home dir, and UUID and fixing ownership and flags...not that I expected this to have any effect, and it didn't. Still broken.

The last response I received from Apple was several weeks ago. I had sent several sets of logs to them. They appeared to confirm that there was clearly a problem, and seemed to feel it might be a "permissions" issue. Coincidentally, "repair permissions" was completely removed from macOS Sierra. They promised a "hot fix," which I had hoped would be in 10.12.1, but clearly wasn't, though a few have reported resolution with 10.12.1. Since my "Little Snitch" installation resolved the problem for me—it remains resolved even after several weeks and lots of "hard use,"—they have closed my case and I haven't had other communication with anyone from Apple, although I continue to follow this thread.

Recently, some people have reported success using a fix suggested by qkoziol, in this thread: Mac Os Sierra keep logging out !! It is simply deleting com.apple.universalaccess.plist file from ~/Library/Preferences, then rebooting. It has worked for several people and should be completely benign to try. Other fixes have worked for others. None have, unfortunately, worked for others. Apple has endorsed setting up a new account, which seems to work for everyone but, of course, that's no fun! There are other solutions that have worked for yet others, depending upon hardware configuration, that are scattered about the Discussion Groups. Most are referenced in the thread I mentioned above.

If you haven't tried it, I would suggest trying qkoziol's solution. If that doesn't work, and you use Razer Synapse, DuetDisplay, or your problem occurs exclusively with Chrome full-screen video, there are other solutions out there. You can always try my "Little Snitch" installation, which worked for at least a couple of people, including me, but not for lots of others. I don't believe it's the program, itself, that did anything, but something that it "fixed" during installation. I've posted the "Little Snitch" installation log elsewhere, and sent it to Apple. Clearly, this is a problem different groups of people are all getting to via different mechanisms. I'm sad to say that Apple Support, while very well-meaning, courteous, and helpful (at least wanting to be), has not been more forthcoming with a root cause and universal solution.

Worst case scenario: Migration to a new user account; that seems to universally work. I'm sorry I don't have anything else to offer.

johnsalomon wrote:

Have any of those of you working on this with Apple received a reply? I can confirm this persists with 10.12.1

Setting up a new account works, but I'd rather not migrate everything.

Safe mode boot works.

For fun I created a new user, migrated everything from the older user to the new one, including ultimately switching over the UID, home dir, and UUID and fixing ownership and flags...not that I expected this to have any effect, and it didn't. Still broken.

Your symptoms clearly demonstrate that the problem is something in your account.

New user works ok, safe mode works ok.

When you created a user mimicing your own, the problem shows (of course!).

Waiting for an update from Apple to fix it is no solution. You have to figure out what in your account is wrong. Start with the login items. And... did you use cleaners? antivirus?

I can confirm that the solution from qkoziol that Dhalgren shared worked. I couldn't reply earlier because I managed to temporarily brick my laptop (don't ask) due to a permissions issue when creating a new account, fixed it with a recovery terminal though.

Also, yeah, creating a new user was a long shot, but hey, I'd try anything 😀