If an install fails

Getting back to Fastboot Mode

• Restart the phone into Fastboot Mode with its bootloader keys. The supported devices page lists them.
• If it starts Android or keeps restarting on the logo, use the keys again.
• Then press Connect on the installer page. Reload the page first if it shows an error about the USB device.

The phone stopped answering

• The bootloader stops answering when a command is cut off while the phone replies. Only a restart frees it.
• The installer never cuts a reply off. When the phone has not answered for a while, it asks for a restart and sends nothing more.
• Restart the phone into Fastboot Mode with its bootloader keys. Then press Connect and carry on.
• Do not unplug the phone or close the page while a command runs.

It stopped before writing

• A check failed: the phone, its lock state, the release signature or a file of the image set.
• Nothing on the phone changed. Fix what the message names and start again.
• A download whose signature fails, or a file that does not match SHA256SUMS, is damaged or altered. Get the image set again.

A write failed or the phone stopped answering

• After a partial install the phone may not start, or it may keep restarting. It can still be installed.
• Bring it to Fastboot Mode, connect it and press Install again. The install writes everything again from the start.
• If it fails at the same place twice, try another USB port or cable, without a hub.

fastbootd does not start or fails

• Bring the phone to Fastboot Mode and run the whole install again.
• If fastbootd fails again, return to the stock OS as below, then install again.

Unlocking is not allowed

• The phone allows unlocking only while OEM unlocking is on in Developer options.
• When Android starts after the first unlock, it turns OEM unlocking off and greys the switch out. The critical partitions can then not be unlocked.
• Ask for help in that case, and do not lock the phone.

Locking failed or was not confirmed

• An orange warning screen at the start means the bootloader is still unlocked. The phone works unlocked. To lock it, install again and lock straight after.
• If the phone did not return to Fastboot Mode after the critical partitions were locked, the bootloader stays unlocked. Restart the phone into Fastboot Mode with its bootloader keys.
• An install that writes firmware then asks to unlock the critical partitions first.
• If the bootloader refused the lock, do not repeat it. Ask for help.
• Never lock a phone that does not allow unlocking. If it then failed to start, it could not be unlocked again.

Returning to the stock OS

See returning to the stock OS.

Never do these to fix a failed install

• Do not lock the bootloader. A locked phone that does not start may not be recoverable.
• Do not run fastboot -w or erase partitions. The install writes empty images instead.
• Do not switch slots. The install writes the operating system only to the slot its image set names.
• Do not install firmware older than the phone already runs.

Asking for help

Report the problem on the issue tracker. Copy or save the Log at the end of the installer page and add it to the report. It holds no serial numbers.