If your Samsung Galaxy S9 device shows the "System UI Has Stopped" error, then you should be checking the info posted below and learn what you can do to fix your device.
This System UI error is a major one, as it makes your phone unusable and you are left with a broken device. If you are an advanced user and you don't want to take your Galaxy S9 to a professional repair center, then you can find in this article some tutorials that should teach you what actions you can take in order to reset the System UI app and make it work as it did before.
Note that some of the instructions below are going to wipe data from your phone, and you should create backups for the most important data files you have stored on your Galaxy S9. In case you're having trouble applying some of the steps below, then you can tell us in comments and we will try to offer you a different solution - make sure to list as many details as you can about the problems your Galaxy S9 is experiencing.
Reboot Galaxy S9 and Force Stop System UI App:
You should first power off the phone and then reboot it in normal mode. After the boot is complete you can try to unlock it, and if you do you should go to Settings> Apps> show System Apps list and find the System UI App in that list. Open it and force stop it to make it crash again. After this the app should be reloaded completely and if the issue is fixed you will know right away as no crashes will be shown after that.
If the issue continue and the System UI crashes continuously, then you might want to try and apply the changes listed below.
Try to Update Samsung Galaxy S9 to Latest Firmware Update:
Another thing you can try would be to update your Samsung Galaxy S9 to the latest Android firmware files. Go to Settings> Software Updates and use the "Download and Install" menu to complete the installation.
If a new firmware is ready for download you have to confirm process and your device will take care of the rest. After the update is done you should reboot the device once more and check to see if the issue has been resolved.
Reset App Preferences from Settings menu:
The App Preferences of your Galaxy S9 can be restored to their default values and this might fix the problems you are having with the System UI. By resetting the app preferences you will get rid of all changes any app might have applied to some of your phone's system settings. Here's how to do it: go to Settings, then open the Apps menu and tap on the 3-dots icon - select the "reset app preferences" option and confirm the process. Reboot your phone and you are done.
After the reboot you should test some of the apps you have recently installed and see if the System UI app crashes again. If the issue persists you have to continue to the next part of this post.
Boot Phone in Safe Mode and Remove Bad Apps:
This tutorial will show you how to boot in Safe Mode and start removing apps that you suspect are interfering with the way your Galaxy S9 loads the System UI. If the phone is unusable when booted up, then you can boot Safe Mode with the phone turned off, too.
Here's how to boot Safe Mode with the device powered off: power on the Galaxy S9 normally and when the Samsung logo shows up you need to press and hold Volume Down button. Keep the Volume Down button pressed until the Galaxy S9 Safe Mode boot is complete.
In Safe Mode you will only load the default apps your Galaxy S9 has featured since the day you first booted it up. Note that now you can remove all the apps you thing might block the System UI from properly launching on your Galaxy S9. If this doesn't work get to the next tutorial.
Clear System UI App Cache and App Data:
If your phone boots up, and the System UI only crashes randomly, then you could be able to view the app's system storage options. You can clear the values of the System UI like this: go to Settings> Apps> enable "show system apps" option> find System UI app and open its "Storage" menu. In System UI app> Storage menu you need to tap the "clear data" option and confirm the process. Reboot the phone after this action is done.
Wipe Cache Partition from Recovery Mode:
Another thing you can try would be to wipe the cache partition of your Galaxy S9, as this should reset all the cache files your device has stored for every single app you have installed on your phone. Here's how to do it:
- power off the phone.
- press and hold Volume Up + Bixby + Power buttons at the same time.
- wait for the Blue screen to load on your device, then you have to wait 30 seconds more for the Recovery options to load.
- select the 'wipe cache partition' option and confirm the process.
- reboot the phone in normal mode when you are done.
If this doesn't fix the System UI problems you will need to continue to the next step and wipe clean the entire system partition of your phone.
Factory Reset Samsung Galaxy S9 from Recovery Mode:
The last tutorial you have to use in order to try and fix your device would be the Factory Reset one. Before starting the complete wipe of your Galaxy S9 you have to backup all the important data files first. After you backup the files you can start the factory reset process, but note that this will remove all the installed applications and other data stored on the system partition.
Here's how to factory reset your Galaxy S9 from Recovery Mode:
- power off the device.
- boot your phone in Recovery Mode by pressing and holding Volume Up + Bixby + Power buttons at the same time.
- release all buttons when the screen turns blue and wait 30 seconds more for the Recovery Mode options to load.
- select 'wipe data/ factory reset' process and confirm process.
- reboot the phone in normal mode when you are done.
These were all the tutorials and instructions you had to go over in order to learn how to fix the "System UI" error on your Galaxy S9 device. If the issues continue even after you've applied all the steps above, then you should take your Galaxy S9 to a professional smartphone service shop, as they will most probably be able to eaisly determine the issue your device is having.
If you can think of other method that someone could use in order to fix the Galaxy S9 System UI problems, then feel free to let others know in comments.