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Mac Firmware Password - UK Warning!

PostPosted: Sat May 02, 2020 5:59 am
by autolog
Well I got my new Mac mini just over a week ago. :)

I set it up and then used Carbon Copy Cloner to back it up to a 2TB SSD (A vast improvement over using a standard HDD). Having done the initial backup, I wanted to encrypt the disk. You have to do this by booting from the cloned disk and then turn on FileVault. Once the encryption starts you can reboot the Mac and the encryption will carry on once you reconnect the external disk.

All sounds good, but being a new Mac mini you have to enable booting from an External drive having started in recovery mode. I thought this looked potentially dangerous and so decided to set a firmware password. As I didn't want to risk forgetting it, I set it to my Mac sign-in password. All good so far.

I then rebooted in recovery mode to start from the external disk and the Mac asked for my firmware password, which I duly entered and was rejected! :shock:

After numerous attempts (still rejected), I realised that the input field wasn't accepting the \ [backslash] key which is part of my password.

After googling firmware passwords (where the general advice was don't set firmware passwords :wink: ) I discovered that when the Mac initially boots and asks for the firmware level, it assumes that you have a US keyboard attached. There is a subtle difference between the two that involves the \ [backslash] and Return/Enter keys:

Re: Mac Firmware Password - UK Warning!

PostPosted: Sat May 02, 2020 6:14 am
by autolog
The second part of the story (didn't mean to hit submit) :oops:

I should have mentioned in the first post that I did try other key combinations but at the firmware level it doesn't take them.

Contacted Apple who hadn't heard of this problem (although there is mention on google of this!) and said the only solution was to take it to an Apple Store where they would reset the firmware password if I could prove the Mac was mine. Of course all the UK Apple Stores are closed because of the Covid-19 Lockdown.

Luckily at this point I could boot the Mac in normal mode. So I was only at risk if I needed to boot in recovery mode and of course I couldn't encrypt my external drive.

I wondered whether attaching a US keyboard would allow me to circumvent the problem. So looked on ebay and managed to find a second-hand wired US keyboard for £45. Ordered it last Sunday and it arrived on Wednesday - good service from the seller and courier.

I plugged in the US keyboard and typed into a note and the backslash key did nothing! So configured the Mac location to be US, rebooted and set the keyboard to US. Still no joy until I rebooted again and this time the key worked!

So I rebooted in recovery mode and was able to enter my password and get in. :D

The first thing I did was to remove the firmware password. :wink:

I think this is a flaw in the Apple hardware/software - it shouldn't allow you to enter a key that can't be used on a restart.

It has been a stressful (Mac related) week. I thought I would share the story in case it helps any other person who may see this post.

Re: Mac Firmware Password - UK Warning!

PostPosted: Sat May 02, 2020 6:24 am
by neilk
It must be the week for keyboard related screw ups, I managed to fry my wired keyboard with what turned out to be an overly moist anti-bacterial wipe. Again thankfully eBay came to the rescue !

Re: Mac Firmware Password - UK Warning!

PostPosted: Fri May 15, 2020 1:57 pm
by mat
Wow, I am on a new keyboard too - other stopped working after about 8 years so not unhappy!