The Xiaomi Mi MIX 2S (codename polaris), launched in 2018, was the refined and powerful evolution of the revolutionary MIX series. It retained the stunning, nearly bezel-less full-screen design and premium four-sided curved ceramic body of its predecessor while introducing massive internal upgrades. The MIX 2S was a true flagship, powered by the Qualcomm Snapdragon 845 chipset and featuring a highly-rated AI dual-camera system. It was also the first in the series to support Qi wireless charging. For owners of this design-forward flagship, this page provides official fastboot ROMs for China, Global, and Russia, alongside the popular Xiaomi.eu custom ROM and the essential TWRP custom recovery.
Important: You must verify your device is a Mi MIX 2S (polaris). This firmware is not compatible with the earlier Mi MIX 2 (chiron) or the later Mi MIX 3 (perseus). Flashing the wrong firmware will hard brick your phone.
Quick Device Specs
- Device: Xiaomi Mi MIX 2S (polaris)
- Release year: 2018
- Chipset: Qualcomm Snapdragon 845
- Display: 5.99″ IPS LCD, Full Screen Display
- Battery: 3400 mAh, 18W wired & 7.5W wireless charging
- Original MIUI: Android 8.0 (Oreo), MIUI 9
Required Downloads
| File / Tool | Download Link |
|---|---|
| Xiaomi Mi Flash Tool | Download Latest Version |
| Xiaomi USB Drivers | Included with Mi Flash Tool |
| Bootloader Unlock Tool | Official Mi Unlock Page |
Official & Custom ROMs / Recovery
| Region | Build | Android | Type | Download | Codename |
|---|---|---|---|---|---|
| China | V12.5.1.0.QDGCNXM | 10.0 | Official Fastboot ROM | Download | polaris |
| Global | V12.0.3.0.QDGMIXM | 10.0 | Official Fastboot ROM | Download | polaris |
| Russia | V12.0.2.0.QDGRUXM | 10.0 | Official Fastboot ROM | Download | polaris |
| Xiaomi.eu (Custom) | V12.5.1.0.QDGCNXM (Based) | 10.0 | Custom Recovery ROM | Download | polaris |
| TWRP (Custom Recovery) | 3.3.2B | — | Custom Recovery | Download | polaris |
How to Flash Official ROM (Mi Flash Tool)
Use this method to unbrick your phone or restore official MIUI firmware.
- Boot into Fastboot mode (Power + Volume Down).
- Extract the official firmware (.tgz file) and select the main folder containing the
/imagesdirectory in Mi Flash Tool. - Select clean all for a safe installation (you can use clean all and lock to return to a fully stock, locked state).
How to Install TWRP & Flash Custom ROMs
Use this method to install the Xiaomi.eu custom ROM or other community-developed ROMs.
What is TWRP? TWRP (Team Win Recovery Project) is a powerful custom recovery that replaces your phone’s limited stock recovery. It is the essential tool that allows you to install custom software (.zip files), create full backups of your system (a “Nandroid”), and perform other advanced maintenance. The official ROMs on this page do not require TWRP.
Disclaimer: This is an advanced process. Proceed at your own risk.
- Unlock the Bootloader: This is a mandatory first step. Use the official Mi Unlock Tool.
- Flash TWRP:
- Boot your phone into Fastboot mode (Power + Volume Down) and connect it to your PC.
- Using ADB & Fastboot tools on your PC, flash the downloaded recovery-TWRP-3.3.2B…img file with the command:
fastboot flash recovery recovery-filename.img
- Boot into TWRP: After flashing, immediately boot into recovery by holding Power + Volume Up.
- Install Custom ROM:
- In TWRP, it’s recommended to first go to “Wipe” and select “Format Data” to prevent encryption issues.
- Transfer the Xiaomi.eu .zip ROM file to your phone.
- In TWRP, tap “Install,” select the .zip file, and swipe to confirm the flash.
- Reboot your system once complete.
FAQs
Q1. What were the main upgrades in the Mi MIX 2S over the Mi MIX 2?
The main improvements were internal. The Mi MIX 2S moved to a much more powerful Snapdragon 845 processor (from the 835), introduced a significantly better AI-powered dual-camera system that scored highly on DxOMark, and added support for Qi wireless charging.
Q2. Can I flash a Mi MIX 3 (perseus) ROM on my Mi MIX 2S?
No, absolutely not. The Mi MIX 3 has a different form factor (a magnetic slider) and different hardware components. Their firmwares are not interchangeable, and flashing the wrong one will brick your device.
Q3. What was the final official update for the Mi MIX 2S?
The Mi MIX 2S launched with Android 8.0 Oreo and received its final major OS upgrade to Android 10. The MIUI 12.5 build for the China region was the last significant software update for this model.
Q4. The Xiaomi.eu ROM is a .zip file. What does that mean?
It means it is a “Recovery ROM” that must be installed from within a custom recovery environment. The provided TWRP file is the tool you need to flash first, which then allows you to install the Xiaomi.eu .zip file.
Troubleshooting
- Drivers: If your PC does not recognize the phone in fastboot mode, reinstall the Xiaomi USB drivers and run Mi Flash Tool as Administrator.
- Fastboot errors:
- “error: not catch checkpoint” → This common error means you have selected the wrong folder. In Mi Flash Tool, be sure to select the parent folder that was created when you extracted the .tgz file, not the images folder inside it.
- “Anti rollback error” → You are attempting to flash an older firmware version than what is currently on the device. Xiaomi’s Anti-Rollback Protection (ARB) prevents this.
- TWRP Issues:
- TWRP asks for a password → This means your phone’s storage is encrypted. The standard fix is to go to the “Wipe” menu in TWRP and choose “Format Data”. This will erase everything on your internal storage.
- Stuck on boot after flashing → If the phone doesn’t boot up after flashing a custom ROM, reboot to TWRP, perform a full wipe (Cache, Dalvik, System, Data), and then re-flash the ROM .zip file.
