What to do if Galaxy S9 has “Unfortunately system UI has stopped” bug [troubleshooting guide]

One of the most common bugs Samsung devices encounter is “Unfortunately system UI has stopped”. In today’s #GalaxyS9 troubleshooting episode, we’ll show you how to handle it if you experience it on your device.

What is System UI app?

System UI app is one of the core apps in your device responsible for making sure Android User Interface is working. User Interface or UI is the thing that you interact with in order to send your commands to the operating system. For example, when you’re on your phone’s Home page, the UI is the software component that captures your touches in order to tell Android that you want to open Facebook app. UI includes all user-facing components like launchers (whatever you’re using). By default, the launcher on your S9 is the one supplied by Samsung but there are other good alternatives that you can use too. So, whenever you get the “Unfortunately system UI has stopped” pop-up it can mean there’s an issue with the System UI app itself, or with one of its associated components like the launcher you’re using.

How to fix the “Unfortunately system UI has stopped” bug on your S9

There’s a list of possible reasons why “Unfortunately system UI has stopped” bug appears. In this troubleshooting guide, well tell you how to troubleshoot this error.

Force reboot your S9

Many users who encountered “Unfortunately system UI has stopped” in multiple devices were able to fix this bug by doing a simple reboot. It’s possible that your particular case may be caused by a temporary software bug and restarting your S9 might fix it. Make sure that you restart your phone by simulating a “battery pull,” also known as soft reset, instead of doing the regular one. To soft reset your S9:

  1. Press and hold the Power + Volume Down buttons for approximately 10 seconds or until the device power cycles. Note: Allow several seconds for the Maintenance Boot Mode screen to appear.
  2. From the Maintenance Boot Mode screen, select Normal Boot. Note: Utilize the volume buttons to cycle through the available options and the lower left button (below the volume buttons) to select. Also, allow up to 90 seconds for the reset to complete.

Uninstall recently installed third party app

If the “Unfortunately system UI has stopped” error started showing up after you installed a new app, chances are that app may be to blame. The same can be said if you recently installed an update for a new app. In many cases in the past, “Unfortunately system UI has stopped” bug also occured after users installed apps outside of the Play Store. If you did any of these things, make sure to uninstall whatever that app to fix the problem. If you can’t recall ever installing any new app lately, just skip this step.

Check for rogue apps

Even if you did not install any new app recently, that does not you can totally eliminate the chance of a third party app causing an issue. In fact, the very opposite is true in this case. There’s been a lot of “Unfortunately system UI has stopped” cases caused by a apps before. To check if one of your apps is to blame, run your phone on safe mode and observe.

While on safe mode, third party apps and services won’t be allowed to run so if the problem won’t occur in this mode, you can bet you have a bad app issue.

If you haven’t tried observing your S9 to safe mode before, here’s how to do it:

  1. Turn the device off.
  2. Press and hold the Power key past the model name screen.
  3. When “SAMSUNG” appears on the screen, release the Power key.
  4. Immediately after releasing the Power key, press and hold the Volume down key.
  5. Continue to hold the Volume down key until the device finishes restarting.
  6. Safe mode will display in the bottom left corner of the screen.
  7. Release the Volume down key when you see Safe Mode.
  8. Let your S9 run in this mode for several hours and check for the problem.

If your S9 turns on to safe mode but not on normal mode, that’s a clear sign that one of your apps is indeed problematic. To know which app is causing a problem, follow these steps:

  1. Boot to safe mode.
  2. Check for the problem.
  3. Once you’ve confirmed that a third party app is to blame, you can start uninstalling apps individually. We suggest that you begin with the most recent ones you added.
  4. After you uninstall an app, restart the phone to normal mode and check for the problem.
  5. If your S9 still refuses to power back on, repeat steps 1-4.

Uninstall Google app updates

Some users were reportedly able to fix “Unfortunately system UI has stopped” bug by dealing with Google app. In a way, this can make sense given the fact that System UI app, as we’ve mentioned above, does not work on its own. It needs other apps to perform tasks and if one critical app has a bug, it’s possible that other apps may suffer performance issues as well. In this particular troubleshooting step, what you want to do is uninstall Google app updates. Don’t worry, this will not affect any Google services you may be using. If necessary, you can always reinstall the Google app updates.

In order to uninstall Google app updates, follow these steps:

  1. Open Settings app.
  2. Tap Apps.
  3. Tap More settings at the upper right (three-dot icon).
  4. Tap Show system apps.
  5. Find and tap Google app.
  6. Tap More settings at the upper right (three-dot icon).
  7. Tap Uninstall updates option.

Clear cache partition

In some cases of “Unfortunately system UI has stopped” bug, dealing with the system cache helps so if the problem is still not resolved at this point, be sure to try clearing the cache partition. Android uses partitions to perform tasks and in loading app quickly, it utilizes the system cache, kept in the cache partition. To see if you have a system cache problem, follow these steps:

  1. Turn off the device.
  2. Press and hold the Volume Up key and the Bixby key, then press and hold the Power key.
  3. When the Android logo displays, release all three keys.
  4. An ‘Installing system update’ message will show for 30 – 60 seconds before the Android system recovery menu options appear.
  5. Press the Volume down key several times to highlight wipe cache partition.
  6. Press Power key to select.
  7. Press the Volume down key to highlight yes, them and press the Power key to select.
  8. When the wipe cache partition is complete, Reboot system now is highlighted.
  9. Press the Power key to restart the device.

Force Stop System UI app

If the problem is not yet fixed by this time, the next troubleshooting step that you can do is to ensure that you force quit System UI app itself. This worked for other users in the past so you should try it as well. Here’s how to do it:

  1. Open Settings app.
  2. Tap Apps.
  3. Tap More settings (three-dot icon) at the upper-right.
  4. Tap Show system apps.
  5. Find the app and tap it.
  6. Tap FORCE STOP button.
  7. Restart your S9.
  8. Check if the problem still exists.

Clear cache of System UI app

Another good way to directly deal with the System UI directly is by clearing its cache. You should do this if the problem continues after force stopping the app.  Clearing an app cache is simple. Here’s how:

  1. Open Settings app.
  2. Tap Apps.
  3. Tap More settings (three-dot icon) at the upper-right.
  4. Tap Show system apps.
  5. Find the app and tap it.
  6. Tap Storage.
  7. Tap CLEAR CACHE button.
  8. Restart your S9.
  9. Check if the problem still exists.

Factory reset

If all our suggestions above won’t work, the final troubleshooting step that you can do is to wipe the phone and restore its software settings to defaults. Such action will erase all non-system critical apps, services, and data from the phone. It also will revert all software settings back to their factory state, which is free of “Unfortunately, phone has stopped” error. Here’s how to do it:

  1. Back up data on the internal memory. If you have signed into a Google account on the device, you have activated Anti-theft and will need your Google credentials to finish the Master reset.
  2. Turn off the device.
  3. Press and hold the Volume Up key and the Bixby key, then press and hold the Power key.
  4. When the Android logo displays, release all keys (‘Installing system update’ will show for about 30 – 60 seconds before showing the Android system recovery menu options).
  5. Press the Volume down key several times to highlight “wipe data / factory reset.
  6. Press Power button to select.
  7. Press the Volume down key until ‘Yes — delete all user data’ is highlighted.
  8. Press Power button to select and start the master reset.
  9. When the master reset is complete, “Reboot system now” is highlighted.
  10. Press the Power key to restart the device.

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