Many are asking about to update/upgrade to MIUI 12 ROM from MIUI 11 or want to downgrade ROM from MIUI 12 to MIUI 11, but will have issue with unlocking the bootloader.
After you unlock the device, it will become less secure. Your personal data might be leaked or lost. So we do not advise and encourage you to Unlock your device. So please proceed at your own risk, and you are held responsible for your own device.
Visit http://en.miui.com/unlock and apply for unlocking your device.
Download Mi Unlock tool to your PC & Extract it.
mi unlock tool – direct download link
Go to Setting > About Phone > All Specs and tap on MIUI Version 7 times
Enable Enable USB Debugging and Enable OEM Unlocking. Go to Setting > Additional Setting > Developer Options > Enable USB Debugging and Enable OEM Unlocking.
Now from Developer Option add your account to “Mi Unlock status”. Disable Wi-Fi connection and bind your account.
After, reboot your device into fastboot , for this just restart your device and keep push volume down ( – ) button. Then connect the device to the Windows PC/laptop via a micro USB cable.
Launch Mi Unlock Tool via run as administrator.
Follow the steps from the app and unlock your bootloader.