Enable OEM unlocking and follow the instructions. You might need to enter the PIN, password or pattern for unlocking the lock screen of your FP3

Using /e/OS Settings
,
1

Try to https://www.fairphone.com/en/bootloader-unlocking-code-for-fairphone-3/ unlock Fairphone3

Input verify code : warning,
and ‘enable’ remains greyed out. No unlocking possible.

How to enable Input verify code ?

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