[Xiaomi Mi CC9 / Mi 9 Lite Guides, News, & Discussi] iuliusdeblobbis:
DISCLAIMER: First off, I'm not a dev; I'm someone with a lot of time to spare that's trying to save quite a few headaches to people that don't like MIUI. If you're actually one of the talented people that worked on this stuff and don't like seeing your work shared here, just hit me up.

Secondly, all of this has been tested on my Mi 9 Lite. I can't guarantee it'll work on other variants such as the meitu edition or the Mi CC9, but then again I can't see why it wouldn't.

Lastly, please take all your due precautions before doing this: take your backups, be sure to have a plan in case anything goes wrong, the whole deal.

INSTRUCTIONS:

0) Unlock your bootloader and flash Brigudav's TWRP;

1) Format your data partition. This is mandatory, you need to get rid of the encryption!

2) Download and flash the latest Unofficial LineageOS 16 by gringo80. Compared to the xiaomi.eu build that I recommended before, the Vendor from LOS enables the use of the wide angle lens in GCam, Hypercam and ANXCamera.

3) Reboot into TWRP without booting into system; this ensures that the System partition is properly mounted before proceeding;

4) Under "Advanced Wipe", select the Cache, Dalvik, Data and System partition, but don't select "Vendor". Wipe them;

5) Download the A/B HavocOS 2.9 GSI, extract it and place the .img file into your phone's storage;

6) Under "Install", press "Install image file", select the GSI and flash it into the System partition;

7) Flash the nano OpenGapps (ARM64) package for Android 9.0;

7a) If you get an error that says that the System partition is too small, follow these steps: Wipe > Advanced Wipe > Select the System partition > Repair or Change File System > Resize File System. Flash the GApps package again and it should work;

8) Boot the phone, set it up and enjoy!

8a) If you need root, once you've passed the initial setup simply reboot into TWRP and flash Magisk 20.1.

GSIs' COMMON PROBLEMS AND FIXES:

To get Viper4Android working, install the V4A 2.7 apk from XDALabs, flash the GSI Enabler Magisk Module;

If your FOD is slow or inaccurate, set up the same finger twice;

To get ANXCamera working, be sure that the "ro.product.device" string's value in your build.prop file is set to "pyxis" and to have downloaded the "139.PastAdorableHawaiianmonkseal" build.

If you use Titanium Backup to restore your apps, the restoring process might get stuck on certain apps (for instance, Solid Explorer, Sound Cloud, Google Photos and so on). To fix this, simply go to the Play Store and manually download the app. Once it finishes installing, the backup will resume automatically;

To fix the Bluetooth audio in-call not working, flash this Magisk module.

BUGS:

DT2W doesn't work;

You might experience a slightly worse cellular reception depending on your phone's model;

That's... pretty much it!

STUFF THAT WORKS EVEN THOUGH I TOTALLY EXPECTED IT TO FAIL:

EdXposed (SandHook). If you experience sporadic SystemUI crashes, it's Gravity Box's fault;

The Screen OC Mod posted by [MENTION=8855101]HelloRickyLee[/MENTION]. I use the 72Hz dtbo file, since everything above that freezes my phone once I press the power button, but hey! Not complaining!

And that's pretty much it.

Enjoy!

Credits: The HavocOS team; xiaomi.eu team; [MENTION=9222803]gringo80[/MENTION], [MENTION=5724547]brigudav[/MENTION],