Installing custom themes in.mtz format on Xiaomi smartphones with a MIUI 12 shell allows you to radically change the appearance of the system by adding unique icons, animations and design styles. However, standard methods through Themes → Import often do not work due to manufacturer limitations. In this article, we will analyze all the steps from preparing the device to the final activation of the theme, including bypassing locks and solving typical errors.
It is important to understand that MIUI 12 (especially on global and Chinese firmware) actively resists third-party modifications. Therefore, successful installation of MTZ will require not only downloading the theme file, but also performing a number of technical manipulations - from unlocking the bootloader to editing system files. If you are a beginner, we recommend that you carefully follow the instructions and create backups of data.
What is it? MTZ-Themes and why they are not set in a standard way
.mtz files are MIUI theme archives containing graphical interface elements, sounds and configuration files. Unlike the official Mi Theme Store themes, custom MTZs are created by enthusiasts and distributed through third-party resources (e.g., XDA Developers or 4PDA).
The main problem is to block the installation of unsigned themes at the system level. MIUI 10, Xiaomi tightened security policies, and MIUI 12, this mechanism works even harder. MTZ-If you try to import it through the standard Topics menu, the system will give an error "Impossible to apply the theme" or simply ignore the action.
- 🔍 Reason 1: The lack of a Xiaomi digital signature in the theme file.
- 🔒 Reason. 2: Locking the installation through miui_themes (system-application).
- 📱 Reason 3: Restrictions on modified firmware (if you have Global Firmware) ROM).
The problem can be solved in two ways:
- Through unlocking the bootloader and installing a custom recaveri (for example, TWRP), which allows you to flash a modified Theme application.
- Through ADB-commands (no unlocking) if your firmware supports debugging.
Preparation of the smartphone: unlocking the bootloader and enabling debugging
Before installation MTZ-This is a critical step, because it doesn't have the bootloader unlocked or the debugging enabled. USB Further action will be impossible.
If you plan to use the method with TWRP, unlocking the bootloader is mandatory.
- Go to Settings → About Phone → MIUI version and tap 7 times on the line to activate Developer Mode.
- Back to Settings → Additionally. → For developers and include: 🔧 Debugging by USB 🔓 Unlocking OEM (if)
fastboot oem unlock⚠️ Warning: Unlocking the bootloader will reset all data on the device! create a backup in advance.
The ADB method does not require unlocking, but it is necessary to:
- 🔌 Turn on Debugging. USB (see above).
- 🖥️ Install ADB and Fastboot Tools on PC.
- 📱 Confirm the debugging permission at the first connection to the computer.
☑️ Preparation for installation MTZ
Method 1: Install MTZ via TWRP (for unlocked devices)
This method is suitable for users who have already unlocked the bootloader and installed a custom Recovery TWRP. It allows you to flash a modified Theme app that removes installation restrictions. MTZ-file.
Steps:
- Download the modified MiuiHome.apk and MiuiThemeEditor.apk (for example, with 4PDA or XDA).
- Reboot the device in TWRP (hold Power + Volume up).
- V TWRP Choose Install and click on the downloaded APK-file.
- Reboot to the system and try importing. MTZ-File via the standard Topics menu.
If the topic does not apply, try:
- 🔄 Reinstall MiuiThemeEditor with rights system/app.
- 📂 Place it. MTZ-file /sdcard/MIUI/theme/.
- 🔧 Clear the app cache Themes in the settings.
| Problem. | Reason. | Decision |
|---|---|---|
| The topic does not appear on the list | The wrong structure MTZ-file | Check the file for integrity or download another file. |
| The "Theme is damaged" error | Incompatible with MIUI 12 | Look for topics marked MIUI 12+ |
| The application of the theme is reset after rebooting | No rights to write to /data/system/theme/ | Use the MIUI Theme Fix module and use the Magisk Theme Fix module |
💡
If the interface started to get glitzy after the firmware MiuiHome.apk, try rolling back to the standard version via TWRP or clearing the data of the Launcher application.
Method 2: Install MTZ via ADB (without unlocking)
For users who don’t want to unlock the bootloader, there’s an alternative method using ADB. It works on some MIUI 12 firmware, but doesn’t guarantee 100% results.
Instructions:
- Connect your smartphone to your PC and open the command line in the folder with ADB.
- Execute the command to copy MTZ-File to system folder: adb push your theme.mtz /sdcard/MIUI/theme/
- Set file rights: adb shell chmod 644 /sdcard/MIUI/theme/your theme.mtz
- Restart the device and try applying the theme through Themes → Import.
If standard importation doesn’t work, try an alternative method through ADB:
adb shell am start -n com.android.themes/.activity.ThemePreviewActivity -d file:///sdcard/MIUI/theme/ your topic.mtz⚠️ Attention: On some firmware MIUI 12 (especially Global Stable) this method may not work due to additional signature checks, in which case only the option of unlocking the bootloader remains.
What if the ADB can’t see the device?
How to Check Compatibility MTZ-topic MIUI 12
Not all. MTZ-topics compatible with MIUI 12. Many files were created for earlier versions of the shell (MIUI 10/11) They may not be displayed correctly or installed at all. To avoid problems, pay attention to the following parameters:
- 📌 Version. MIUI: Look for tagged topics MIUI 12+ Android 10/11.
- 📱 Device model: Some themes are optimized for specific smartphones (e.g. Redmi Note 9 Pro or Mi 10).
- 🎨 Type of theme: Full topics (Full) MTZ) It replaces all interface elements, while Lite MTZ It only affects icons or wallpaper.
Before installing, check the file for:
- 🔍 Archive Integrity: Unpack MTZ through 7-Zip — There should be a description folder with a file inside. theme_values.xml.
- 📝 Availability of manifesto: In file theme_values.xml should be a line <miui_theme_version>12</miui_theme_version>.
If you downloaded a topic from an unknown source, we recommend that you check it for viruses through VirusTotal. MTZ-Files may contain malicious code masquerading as system modifications.
Solving Common Mistakes When Installing MTZ on MIUI 12
Even with the right device, users often encounter errors, and let's look at the most common problems and how to fix them.
| Mistake. | Possible cause | How to fix it |
|---|---|---|
| "Impossible to apply the topic." | Blocking the system due to lack of signature | Use TWRP + Modified Theme App |
| Theme applies, but resets after rebooting | No rights to write to /data/system/theme/ | Install Magisk and MIUI Theme Fix Module |
| Icons or fonts don't change | Incomplete theme (missing elements for MIUI 12) | Look for Full MTZ with support for your shell version |
| Themes app flies out | Conflict with modified system files | Clear the cache and application data or reinstall it via TWRP |
If none of these methods worked, try:
- 🔄 Reverse to an earlier version MIUI: Some topics work better on MIUI 11.
💡
The most reliable way to install MTZ on MIUI 12 is to unlock the bootloader + TWRP + modified Theme application. The ADB method does not work on all firmware and requires experimentation.
Where to download quality MTZ-topic MIUI 12
Choosing a reliable source for downloading MTZ-themes is critical, as many sites distribute outdated or corrupted files.
- 🌐 XDA Developers: Xiaomi Themes section with proven themes and instructions.
- 📱 4PDA: Russian-speaking community with a large archive of topics for different versions MIUI.
- 🎨 Mi-Themes: Specialized site with catalog MTZ-Files (check reviews before downloading).
- 💬 Telegram channels: For example, @MIUIThemes or @XiaomiCustom (Look for relevant links).
When choosing a topic, pay attention to:
- 📅 Date of publication: The topic should not be older than 2022-2023 (for the first time) MIUI 12).
- 📋 Supported Devices List: Some themes are optimized for AMOLED-screens or specific models.
⚠️ Attention: Avoid downloading MTZ-Files from questionable file sharing sites (such as MediaFire without verification) are often spread under the guise of Trojans masquerading as system updates.