[Xiaomi Mi 8 Questions & Answers] Agimax:
So you bought a shiny new Chinese model, and want to convert to Global or EU version?

I had bought the Chinese version also, and couldn't find a solid method for converting to the Global or EU ROMs. I was worried i would brick my device like so many others! After finding bits and pieces in lots and lots of xda threads, MIUI forums, and finding some mis-information, i decided to put a working method all in one place!

**WARNING***

I am NOT responsible for anything that goes wrong or you have issues with the information i have provided, it worked for me and proceed at your own risk!

FIRST

Unlock your bootloader locked Chinese version phone! (It's a LONG wait)

see official unlock page here-->http://en.miui.com/thread-246705-1-1.html

After Bootloader Unlock

1.) Download TWRP from the page here-->https://xdaforums.com/mi-8/development/recovery-twrp-3-2-3-0-mi-8-t3837745

-- RENAME YOUR DOWNLOADED RECOVERY FILE TO "recovery.img"

2.) Download the DM Verity Disabler here-->https://androidfilehost.com/?fid=3700668719832238534

3.) Download the Region Fix here-->https://www.androidfilehost.com/?fid=1322778262904000068

4.) Download a Global ROM / EU ROM of your choice!

Installing the TWRP Recovery:

Make sure you have a working copy of FASTBOOT on your computer compatible with Mi8 (I used the one in the directory from the Bootloader UNLOCK program)

1.) Copy all of your downloaded files to the Bootloader Unlocker main directory (or a directory with the Fastboot.exe file)

2.) Open a DOS shell prompt on your computer and change the directory to the Bootloader Unlock directory (or Fastboot.exe directory)

3.) Put your phone in to Fastboot Mode (Turn on phone and hold the Volume Down while also holding Power Button)

4.) Connect your phone via USB cable to your computer

5.) In your DOS shell prompt enter this between the quotes "fastboot.exe boot recovery.img"

6.) After your phone boots up with the TWRP, copy the recovery.img file to the main directory of your SDCard

(Your recovery should allow you to open your phones internal storage on your computer)

7.) Install from the TWRP recovery menu (choose IMG file on bottom right, and select the recovery.img from your storage, and choose the Recovery partition to flash to)

8.) After successful TWRP flashing to your recovery partition, Reboot to RECOVERY

Preparing & Flashing Your Downloaded ROM:

1.) Format your data (must be done from the wipe directory where you have to type the word "yes")

2.) after the format, once again reboot to your RECOVERY

3.) Copy your chosen ROM zip file, recovery.img file, Region Fix file, and DM Verity disabler file to your internal phone storage

4.) Install your chosen ROM (flash through TWRP)

5.) Flash your recovery.img file again! (choose IMG file on bottom right of screen, and select the recovery.img from your storage, and choose the Recovery partition to flash to)

6.) Flash the Region Fix file

** Optional of flashing Magisk (v17.1) now if you want **

7.) Flash the DM Verity disabler file

8.) Format DATA again (this removes all of your file from internal storage, so copy them back if you want after the format is done)

9.) Reboot to SYSTEM and Enjoy!

Some steps may be redundant or not needed, however -i spent countless hours in bootloops, reflashes, testing. This method works, and is what i follow every new ROM i install. I am now on the latest Miui10.8.9.6 Global.

Additional Notes:

DON'T downgrade versions of ROMs (ex, miui10 to 9, or miui9 to 8) Anti-Rollback isn't enabled to brick yet (it's only "1")

If you don't flash the Region fix on a Chinese phone, it will constantly reboot, during initial rom setup or won't even make it that far (wish i knew this before, it would have saved me many hours in bootloops)

If you want to STAY on Chinese rom versions with the bootloader locked, you CAN flash miui Chinese developer edition (ex miui10.8.30) using the internal software updater without issues (i did this while waiting for unlocking delay).