Why Xiaomi Redmi 9 is always on wallpaper — and how to fix it once and for all

You've installed beautiful wallpaper on your Xiaomi Redmi 9, but after a reboot or a few hours later, the screen meets you again with a standard background from MIUI? This problem is familiar to many owners of budget Xiaomi smartphones - and it's not always associated with a firmware bug. 80% of the time, the system settings, conflicting applications or even the features of energy-saving modes are to blame.

In this article, we're not just going to list the possible causes, but we're going to look at each of them from a technical perspective, and you're going to learn why wallpaper is reset to default after you upgrade MIUI, how it's related to this problem of app access rights, and why sometimes you just need to turn off one tick in your settings to forget about the problem forever, and you're going to get a checklist of actions that will help restore the stability of the wallpaper in 10 minutes.

1. MIUI System Optimization: Why It Removes Your Wallpaper

The main reason for the Redmi 9's random wallpaper reset is because of the aggressive MIUI optimization policy, which is that the system treats the user's wallpaper as "temporary data" that can be cleared to free up memory, which happens in three cases:

• 🔄 Autocleaning the cache: MIUI Regularly deletes the cache of applications, including wallpaper data, if they were not "fixed" in the system.
• 📉 Lack of memory: When free space falls below 1 GB, the system begins to clean “unnecessary” files – and the wallpaper falls under the distribution.
• ⚡ Energy saving: In the ultra-low consumption mode MIUI suspends background processes, including wallpaper service.

To see if you're doing optimization, open Settings → Memory → Cleanup and see if you've recently done automatic space vacancy. If so, that's the problem.

💡

Turn off automatic cache cleaning for the Wallpaper application via Settings → Applications → Application Management → Wallpaper → Memory → Cache cleaning (set the switch to the "Off" position).

2. Conflict with wallpaper apps: who is to blame and what to do

If you install wallpapers not through the standard MIUI application, but through third-party services (such as Zedge, WallpapersCraft or Backdrops), there is a high risk of conflict.

• 📥 Upload the wallpaper to a temporary folder that MIUI cleans.
• 🔒 Do not request permanent storage of files.
• 🔄 Rewrite wallpaper settings at each launch.

The most reliable way is to use Xiaomi's built-in Wallpaper app, but if you need wallpaper from third-party sources, follow this instruction:

Download wallpaper to the gallery (do not install it directly)|Open the standard Wallpaper app |Select the downloaded image from the gallery |Click "Install" and confirm the selection |Reboot the phone to check-->

If the wallpaper still goes off, delete the third-party app and check the result, and 60 percent of the time, it solves the problem.

3. Firmware errors: when the software is to blame

Some versions of MIUI for Redmi 9 (especially MIUI 12.0.8 and MIUI 12.5.1) contained bugs that prevented wallpaper settings from being stored in the registry.

• 🖼️ The wallpaper was reset after each reboot.
• 📱 On the lock screen and desktop displayed different wallpaper.
• ⚙️ In the settings of the wallpaper there was an error "Can not apply".

Decisions:

1. Update MIUI to the latest stable version via Settings → About Phone → System Update.
2. If the update does not help - reset the settings of the Wallpaper application: Settings → Annexes → Application management → Wallpaper. → Warehouse → Clear the data ⚠️ Note: This will remove all saved wallpaper, but will return the functionality.
3. In extreme cases, try to use the Mi Flash Tool (instructions below in the section about radical methods).

MIUI 12|MIUI 12.5|MIUI 13|MIUI 14|I don't know.-->

4. Problems with access rights and system folders

The wallpaper in MIUI is stored in a secure system folder /data/system/users/0/wallpaper. If the Wallpaper app doesn't have permission to write to that directory, the changes won't persist.

• 🔓 Rooting the phone (getting root rights).
• 🛠️ Installations of custom recaveri (TWRP).
• 📁 Cleaning Dalvik cache manually.

How to check and correct:

1. Open Settings → Applications → Permissions → Application Rights and find “Wallpaper”.
2. Make sure the application has storage rights and changes to system settings.
3. If you are using root, check the folder permissions /data/system/users/0/ via Root Explorer: chmod 755 /data/system/users/0/chown system:system /data/system/users/0/

5. Energy saving modes and background optimization

Redmi 9 is known for its aggressive energy saving policies, which sometimes go too far.

• ⚡ Ultra-low power consumption (Settings) → Battery → Battery mode).
• 🔋 Background optimization for the wallpaper application".
• 📵 Limiting background data for system processes.

- then the wallpaper service can be suspended, and its settings reset.

A critical feature of Redmi 9: In this model, background optimization by default blocks system processes associated with personalization if the battery charge drops below 15%.This is done to save energy, but often leads to wallpaper reset.

Decision:

1. Open Settings → Battery → Battery Mode and select Balanced or Performance.
2. Add the Wallpaper app to the optimization exceptions: Settings → Battery → Battery Optimization → All apps → Wallpaper → Not Optimizing
3. Turn off background data restriction in Settings → SIM cards and mobile networks → Data transfer → Background restriction.

Hardware problems: when iron is to blame

If all the software methods have been tried, but the wallpaper still flies, the problem may be in the hardware. Redmi 9 is characterized by two scenarios:

To rule out hardware problems, perform a memory test:

1. Install the AIDA64 app from Google Play.
2. Go to the Test section → Memory.
3. Run a read/write stress test for 10-15 minutes.
4. If you have an error (I/O Error, Bad Block) your memory is broken.

⚠️ Warning: If the test shows memory errors, don't delay repairs. A damaged flash memory can cause complete data loss and phone buildup.

Radical methods: resetting and flashing

If neither of these methods worked, there are two extreme options:

1. Hard Reset: Back up your data via Settings → Additional → Backup. Turn off your phone, then press Volume Up + Power before the Mi logo appears. From the recovery menu, select Wipe Data → Wipe All Data.

⚠️ Note: This method will delete all data, including photos, contacts and messages. Use only if you are ready for a complete reinstallation.

Fastboot flashing through Fastboot

• Download the latest official firmware for Redmi 9 (codenamed Lancelot).
• Install the Mi Flash Tool on your PC.
• Connect your phone in Fastboot mode (clip Volume Down + Power).
• In the Mi Flash Tool, select the downloaded firmware and press Flash.

FAQ: Frequent questions about resetting wallpaper on Redmi 9