Fingerprint reboot on MIUI 12


Voyagerscout

Members
Sep 3, 2020
2
3
Hi Everyone

I have scoured the internet for a solution, but so far I have only found people with the exact same problem.
People who have the Xiaomi Mi 9T Pro / Redmi K20 Pro, report reboots/crashes when trying to use the fingerprint scanner when the following conditions are met:

-They have had their screen replaced
-They have got MIUI 12 installed

With MIUI 11, and other ROMs, the fingerprint scanner works fine. However, after updating to MIUI 12, the device reboots when trying to use the fingerprint scanner.
I have MIUI by Xiaomi.eu 12.0.3 stable installed. but I have seen the same problem with people who have 12.0.1 or 12.0.2 installed, no matter if it is Global, China, EU or xiaomi.eu rom.

Not working:
-Registering Fingerprints in the settings menu
-Unlocking the device with registered fingerprints
-Completing the "FOD fingerprint calibration" in the "Additional Tools" menu of CIT. It fails at the final step, "PERFORMANCE_CHART Test"

Working (albeit buggy):
-The tests in "com.goodix.fingerprint.setting.MainActivity", which can be launced with the app "Activity Launcher"
-CIT Fingerprint Sensor check
-CIT FOD Fingerprint Input Test (I encountered that this test actually registers your fingerprint. After this, the phone immediately crashes, reboots, and your phone is locked! Trying to unlock it reboots the phone. However, you can unlock it with the numerical code "0000", apparently the default password. Unfortunately, this also crashes the phone. To avoid this problem, go into e.g. TWRP, decrypt the storage with "0000", go to Advanced>Filemanager, then go to /data/system/user/0 and delete "settings_fingerprint.xml". After reboot your phone is unlocked)

It seems to me that this is a software issue, since the FOD was working fine in MIUI 11. So far, reports of this issue go back since the first release of MIUI 12 for the Mi 9T Pro.
Xiaomi says the warranty is void once your screen is broken, or replaced.

The only report I found of someone who solved this problem, said the technician who replaced his screen told him he had to "Copy the firmware codes from his old screen to his new screen", but so far no-one was able to follow up on this.

Here are a few links with threads of people reporting the same problem:
Xiaomi.eu
XDA
Baidu

If the xiaomi.eu would be able to fix this issue as opposed to the global/EU/China rom, it would be a major advantage for everyone who has had their screen replaced (which over time will ofcourse be more and more people)
I hope this a bit more comprehensive thread will help us get to a solution.

Thanks :)
 
Last edited:

Voyagerscout

Members
Sep 3, 2020
2
3
Have you tried other custom ROMs, not MIUI ones?
Is the behavior the same?
Yes, I tried Corvus OS and with that the fingerprint is working (a bit slow but working nonetheless).
With MIUI 11 it works very fast. It is only MIUI 12 that causes the problems.
 

vasil_d

Members
Aug 28, 2018
44
20
I see.
I doubt it that the guys/developers from xiaomi.eu will be able to help you in any way.
Firmware stuff is very tricky.
I hope for any of you with that issue that xiaomi will fix the issue, because it seems that only they can.
 
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Sebasyoung

Members
Feb 5, 2020
7
13
I have the same issue, yes i replaced my screen, i only made it work miui12 with the stable one, but fod doesnt work
 

vasil_d

Members
Aug 28, 2018
44
20
Have any of you tried to flash the miui10.3.17 fastboot rom/files? And after that to upgrade to v12 check then?