After Upgrade Unfortunately Settings Has Stopped

[JesseRene]

My sons Redmi Note 3 Kenzo, with official unlocked boot loader, runned fine for a year on a weekly update. 6.5.26 with last Mui 7 for Android 5.0.


After installing the latest official TWRP 3.1.1.0 from twrp.me and installing the latest stable HMnote3PRO 8.2.1.0 Android 6.0 version by TWRP I have the following error if I press on Settings:

Unfortunately settings has stopped.

A Wipe all back to factory settings does not solve the error.
The phone runs fine, he can call, download apps etc.
Except to enter the Settings.

Who can give me a hand in which direction I must search?
Most threads regarding this error only give half information.

Is my boot loader locked again? Do I need to install from scratch with a Chinese developer rom and re open the boot loader?
Did I install the correct rom for Note 3 Kenzo?

Thanks in advance!

 

[Pitada]

Because you are changing the Android version, I think you get locked the bootloader. There is some adb comands in fastboot mode to see that or use the MIUI unlock tool. I think also you need first flash the China marshmallow ROM and then the xiaomi.eu ROM.
I had a similar experience and was the way I solved.
Wish you luck

 

[JesseRene]

Thanks for your reply. I try your suggestion later this week, and write the result.
It sounds weird that if I have an official unlocked boot loader and I'm able to write custom Roms to the device, that it automatically locks after an upgrade from the same xiaomi.eu group. I did not read that this happened to other users after an upgrade from Android 5 to 6.
Perhaps the step was too big for my sons phone indeed.

 

[JesseRene]

My device was stil unlocked.

The only remedy to solve my error was a return to Global dev rom.
Unlock boot loader via unlock tool.
Reinstall TWRP.
Install latest weekly rom.
Thanks for all help!