The Xiaomi Mi MIX 2S (codename polaris) is a masterpiece of early 2018 smartphone design. As a refinement of the revolutionary MIX series, it paired a stunning, minimal-bezel display and a beautiful ceramic back with flagship internals, including the powerful Snapdragon 845 processor and one of the first Xiaomi cameras to feature OIS.
The official software journey for this design icon ended on Android 10, but a familiar software divide occurred: the Chinese variant received a final, highly-optimized MIUI 12.5 update, while Global and Russian users were left on the earlier, buggier MIUI 12.0 build. For the connoisseurs of technology who still cherish their Mi MIX 2S in 2025, this guide provides the path to upgrade to the superior MIUI 12.5 experience, ensuring this work of art remains perfectly functional.
This is the definitive guide for the Mi MIX 2S enthusiast:
Why You Might Need to Flash Your Mi MIX 2S
For a premium classic, flashing is about optimization and preserving the experience.
Quick Device Overview (Codename: polaris)
Required Tools & Downloads
Download the official firmware for restoration and the necessary tools to upgrade to a better experience.
Flashing Methods
Method 1: Upgrading to MIUI 12.5 via Xiaomi.eu ROM (Recommended)
This is the best way to get a modern, stable, and debloated experience on your Mi MIX 2S.
➡ Your Mi MIX 2S will now boot into a clean, optimized MIUI 12.5 system.
Method 2: Flashing Official Stock ROM (For Unbricking/Restoring)
Use this method to restore a bricked device or return to the final official software for your region.
➡ This will restore your phone to its original factory state. This is also the perfect base for installing other custom ROMs.
FAQs
Q1: What is the difference between MIUI 12.0 and MIUI 12.5?
MIUI 12.5 was a major optimization update that focused on making the system lighter, faster, and more efficient. It fixed many of the UI bugs and performance stutters that were present in the initial MIUI 12.0 release, resulting in a much smoother experience.
Q2: Is the Mi MIX 2S still fast in 2025?
Yes. The Snapdragon 845 is a very capable flagship processor. For daily use, social media, and even many modern games, it provides a smooth and powerful experience. Its premium design also helps it feel timeless.
Q3: Can I get Android 11 or 12 on the Mi MIX 2S?
Not officially. However, the polaris has a very strong custom ROM community due to its flagship hardware. You can find many stable, unofficial builds of Android 11, 12, 13, and possibly even newer versions on forums like XDA-Developers.
Q4: Why is the selfie camera on the bottom corner?
This was the signature design of the Mi MIX series, pioneering the move towards truly bezel-less displays. By moving the camera to the bottom "chin," Xiaomi was able to create a stunning three-sided borderless screen. To take a selfie, you simply flip the phone upside down.
Troubleshooting & Common Errors
The official software journey for this design icon ended on Android 10, but a familiar software divide occurred: the Chinese variant received a final, highly-optimized MIUI 12.5 update, while Global and Russian users were left on the earlier, buggier MIUI 12.0 build. For the connoisseurs of technology who still cherish their Mi MIX 2S in 2025, this guide provides the path to upgrade to the superior MIUI 12.5 experience, ensuring this work of art remains perfectly functional.
This is the definitive guide for the Mi MIX 2S enthusiast:
- ✔ A clear path to upgrade your Global/Russian Mi MIX 2S to the superior MIUI 12.5
- ✔ Download links for all final official Fastboot ROMs to unbrick and restore
- ✔ The community-trusted Xiaomi.eu ROM for the best possible MIUI experience
- ✔ A direct link to a working TWRP custom recovery installer
- ✔ A gateway to the custom ROM scene for newer versions of Android
Why You Might Need to Flash Your Mi MIX 2S
For a premium classic, flashing is about optimization and preserving the experience.
- Upgrade to the Superior MIUI 12.5 → This is the best reason to flash today. By installing the Xiaomi.eu ROM, you get the bug fixes, UI smoothness, and performance optimizations that global users never officially received.
- Optimize the Snapdragon 845 → A clean installation ensures the still-powerful flagship processor runs at its peak, unhindered by years of software clutter and background processes.
- Fix Annoying MIUI 12.0 Bugs → Resolve the common notification, control center, and battery drain issues that were present in the initial global MIUI 12 release.
- Create a Clean Base for Custom ROMs → The Mi MIX 2S is a developer favorite. Flashing the latest stock firmware is the perfect first step before installing newer, unofficial versions of Android.
- Unbrick or Fix a Bootloop → The essential recovery guide for restoring a device that is stuck on the Mi logo.
Quick Device Overview (Codename: polaris)
- Model: Xiaomi Mi MIX 2S
- Release Year: 2018
- Chipset: Qualcomm Snapdragon 845
- Display: 5.99” FHD+ IPS LCD
- Key Feature: Premium ceramic back, minimal bezels, wireless charging
- OS at Launch: MIUI 9 on Android 8.0 Oreo
- Final Official OS: MIUI 12.0 (Global) / MIUI 12.5 (China) on Android 10
- Codename: polaris
A Legacy of Design: The Global Mi MIX 2S never officially received the final, optimized MIUI 12.5 update. To get this superior version, which fixes many bugs from MIUI 12.0, users can install the community-made Xiaomi.eu ROM, which is based on the final, more polished China build.
Required Tools & Downloads
Download the official firmware for restoration and the necessary tools to upgrade to a better experience.
| Tool / File | Purpose / OS Version | Download Link |
|---|---|---|
| Mi Flash Tool | For flashing official Fastboot ROMs. | Download Latest Version |
| Xiaomi USB Drivers | Ensures your PC can communicate with your phone. | Driver Pack |
| Mi Unlock Tool | Required to unlock the bootloader. | Official Unlock Page |
| Custom Recovery (TWRP) | Required to flash the Xiaomi.eu ROM. | TWRP for Polaris |
| Fastboot ROM (China) | Official MIUI 12.5 (Android 10) | V12.5.1.0.QDGCNXM |
| Fastboot ROM (Global) | Official MIUI 12.0 (Android 10) | V12.0.3.0.QDGMIXM |
| Fastboot ROM (Russia) | Official MIUI 12.0 (Android 10) | V12.0.2.0.QDGRUXM |
| Xiaomi.eu ROM (Custom) | Recommended MIUI 12.5 Upgrade | V12.5.1.0.QDGCNXM |
Flashing Methods
Method 1: Upgrading to MIUI 12.5 via Xiaomi.eu ROM (Recommended)
This is the best way to get a modern, stable, and debloated experience on your Mi MIX 2S.
- Unlock Bootloader: Ensure your bootloader is unlocked using the official Mi Unlock Tool.
- Flash TWRP: Boot your phone into Fastboot mode (Power + Volume Down). Flash the downloaded TWRP image file with the command:
fastboot flash recovery TWRP-3.3.2B-0302-XIAOMI_MIX2S-CN-wzsx150.img - Boot into TWRP: Hold Power + Volume Up from a powered-off state to boot into the newly installed TWRP recovery.
- Wipe Data: This is a mandatory step. In TWRP, go to Wipe → Format Data and type "yes" to confirm. This removes the stock ROM's encryption.
- Transfer ROM File: Connect your phone to your PC and copy the downloaded Xiaomi.eu .zip file to its internal storage.
- Install the ROM: In the TWRP main menu, tap Install, select the ROM .zip file, and swipe the slider to begin flashing.
- Reboot: Once finished, tap "Reboot System."
➡ Your Mi MIX 2S will now boot into a clean, optimized MIUI 12.5 system.
Method 2: Flashing Official Stock ROM (For Unbricking/Restoring)
Use this method to restore a bricked device or return to the final official software for your region.
- Boot into Fastboot Mode: Power off your phone. Press and hold Power + Volume Down until the Fastboot logo appears.
- Extract Firmware: On your PC, extract the downloaded .tgz Fastboot ROM twice until you have a folder with an images directory.
- Launch Mi Flash Tool: Open the tool as an administrator. Click "select" and choose the extracted firmware folder.
- Connect Device & Flash: Connect your phone, click "refresh", ensure "clean all" is selected, and click "flash".
➡ This will restore your phone to its original factory state. This is also the perfect base for installing other custom ROMs.
FAQs
Q1: What is the difference between MIUI 12.0 and MIUI 12.5?
MIUI 12.5 was a major optimization update that focused on making the system lighter, faster, and more efficient. It fixed many of the UI bugs and performance stutters that were present in the initial MIUI 12.0 release, resulting in a much smoother experience.
Q2: Is the Mi MIX 2S still fast in 2025?
Yes. The Snapdragon 845 is a very capable flagship processor. For daily use, social media, and even many modern games, it provides a smooth and powerful experience. Its premium design also helps it feel timeless.
Q3: Can I get Android 11 or 12 on the Mi MIX 2S?
Not officially. However, the polaris has a very strong custom ROM community due to its flagship hardware. You can find many stable, unofficial builds of Android 11, 12, 13, and possibly even newer versions on forums like XDA-Developers.
Q4: Why is the selfie camera on the bottom corner?
This was the signature design of the Mi MIX series, pioneering the move towards truly bezel-less displays. By moving the camera to the bottom "chin," Xiaomi was able to create a stunning three-sided borderless screen. To take a selfie, you simply flip the phone upside down.
Troubleshooting & Common Errors
- Bootloop after flashing Xiaomi.eu: You must use the "Format Data" option in TWRP before flashing. This is the most common mistake. A simple "Wipe" is not enough to remove the stock ROM's encryption, which causes the bootloop.
- TWRP asks for a password or shows encrypted files: This is a symptom of the issue above. The solution is to use the "Format Data" option in TWRP's Wipe menu. This will wipe your internal storage and decrypt it.
- Mi Flash Tool shows an error or fails: Ensure you have extracted the .tgz file correctly and are running the tool as an administrator. Also, verify the firmware is for polaris and that your USB connection is stable.
- Wireless charging not working: If wireless charging stops working after a software change, the first step is to flash the official stock ROM. This restores all the original drivers and kernel modules. If it still doesn't work, it is likely a hardware issue.