Firmware password works - but deleting it not!

A firmware password can be different than your admin user account login password. Maybe you made them the same, but they don't have to be the same. Also, if you ever changed your admin user account password, it would not change the firmware password since the two items are completely different and unrelated. The password manager has no way of working with the firmware password unless you just used it for storing a reminder note to yourself.

If you don't know the firmware password, then you will need to take the Mac to an Apple Store or an Apple Authorized Service Provider along with valid acceptable proof of purchase and personal ID so that Apple or the AASP can remove the firmware lock for you. If the firmware password does not work for whatever reason and you don't have the necessary acceptable proof of purchase & ID, then there is no way to remove the firmware lock. See this Apple article regarding the firmware lock:

Set a firmware password on your Mac - Apple Support

KnallGrau77 wrote:

I have a really strange bug. I have set up a firmware password on my Macbook Pro (15 inch, 2016). And I also wrote it down in my password manager. I can also log in within the Recovery Mode wonderfully with this password etc..

Recently, I wanted to disable the firmware password so that I can quickly load an alternative operating system from an external hard drive without always having to enter the password.

So I went into the Startup Security Utility to disable the firmware password. There I entered my password, but nothing happened. As if the password is now incorrect. I must have tried it 10 times. No chance. I can't deactivate the firmware protection - even with the correct password I logged in with 1 minute ago!

Then I checked my password via terminal "sudo firmwarepasswd -verify". It seems to be wrong?!?! But I can log in with it? What is wrong?

Does anyone know the problem?

Your admin psswd is required here:

sudo firmwarepasswd -check

do you get feed back on that command?

sudo firmwarepasswd -verify

allows you to verify you have the correct password (without rebooting).

sudo firmwarepasswd -delete

deletes the firmware password. You'll need the current one to delete it, of course.