Just got the tmobile android 12 update on my Oneplus 9pro global version and its causing issues

The System Updater is what is used to apply updates.  It might be called something different in the T-Mobile firmware but that seems unlikely.  Did you select, Show System, when viewing all apps?  

T-Mobile Support was correct to have you reach out to OnePlus.  There are still a lot of people out there that believe carriers produce and push updates, which hasn't been the case since about 2011.  OnePlus support is incredibly hit or miss.  You might want to try the OnePlus forum for your device on XDA or the official OnePlus boards.  I personally don't have a 9 Pro, but I do have a 9, a couple of 8T's, and a couple of 7 Pro's currently.  

Edit:  One thing you might be able to try.  When the update pops up and you pull down the top to see it.  It should have an icon.  Download Package Names from the Play Store and use that to find that particular app name under system.  Then you can find it in your Settings, Apps, Show System Apps, and hopefully be able to force close it.  

System Updater does not exist on the OnePlus 9 Pro, this update seems to be forced by T-Mobile with nothing I can do about it.  TMo support said to reach out to OnePlus Support and oneplus support has had me try all these steps, nothing works.  I've cleared cache, wiped the phone, reset to 11, then as soon as you get on wifi it says the system will be forced to update after April 4th.

“If you choose not to do so now, the update will take place AUTOMATICALLY between 12am and 6am starting April 4th, 2022. 

Data rates my apply.

Please do not turn off your device while the update is installing”

So it sounds like this will even force the 4gb download if wifi is turned off  and it's using mobile data.  Point being, phone really wants to be on Android 12 and on a broken version of Android 12 at that. 

That's odd.  Disabling automatic system updates should stop it from installing regardless of the time.  That is all I do to prevent the next update, even though I do see the notification for it, which I ignore.  If it annoys you to see it in the bar, then go to Settings, Apps, Show System Apps, and force close system Updater.  As soon as you reboot the device though, it will pop back up that the update is available.

syaoran wrote:

Developer Options has an option to turn off automatic system updates.  Tap the build number 7 times to enable Developer Options under System.  

Yeah that doesn't work :)  The only auto update under developer options is "Automatic system updates: apply updates when device restarts". That was the first thing I tried. Phone auto updates over night regardless if that is tapped.

Developer Options has an option to turn off automatic system updates.  Tap the build number 7 times to enable Developer Options under System.  

I've rolled mine back to 11 but then it keeps getting 12 pushed to it with 0 way to block it.  No options in System Update (no gear in the upper right), disabling auto update after reboot in developer settings also does nothing.

Unfortunately 12 introduces a bug where Work Profile cannot be created and therefore I cannot use my phone for work.  I could just keep the phone off from 12-6 am every night and use the auto power off/on, assuming that would work or I could just restore it to Android 11 using MSM every time it updates, but then have to sign into everything again.

Any other way to stop from updating?  Any word on when this bug will be fixed?  

magenta6723572 wrote:

Maybe I’ll try the factory reset first after I backup first.

Some have mentioned a factory reset has solved some minor issues, like Instagram and Facebook apps crashing.  That's about all I have seen a factory reset fix from the 100+ page of complaints on the OnePlus official forums.

Maybe I’ll try the factory reset first after I backup first.

syaoran wrote:

They to to the best of their ability with 5-6 people per model.  Each team is responsible for all regional and carrier variants as well.

Well I’ll just say sarcastically, do a better job 🤣

Minor annoyance as I can rollback but still...this update makes Android look awful.

They to to the best of their ability with 5-6 people per model.  Each team is responsible for all regional and carrier variants as well.