Starting with the Redmi Note 3 MTK, Xiaomi decided to lock its devices' bootloaders. As such, recent devices come with locked bootloaders out of the box. A locked bootloader prevents the user from flashing things in fastboot mode, including flashing custom recovery modes and custom ROMs. Fastboot mode **is** the bootloader, so if it is locked, changes to the device cannot be made in this mode.
### Unlock MIUI devices
1. Go to Settings > Mi Account and log in with your Mi Account.
2. Go to Settings > About phone and tap MIUI version 7 times to enable developer options.
3. Go to Settings > Additional settings > Developer options > Mi Unlock status and add your Mi account and device.
**You will only be able to proceed if it's been more than 72 or 360 hours that you successfully added your account and device. The waiting time depends on the phone model, you can check how much time is remaining by attempting to unlock.**
If you keep getting an error message when trying to add your account and device in developer options, move to a Developer ROM. See the instructions [here](Flash_official_ROMs).