It was 10 PM when I decided to try out Screen Studio, an app that required a system settings change. When prompted for my PIN, I carefully typed it in—or so I thought. After a few incorrect attempts, I was greeted with an error message: "PIN locked."

"No problem," I thought, "I'll just reset it."

The Long Night

I spent the next several hours searching through Apple support forums, Reddit threads, and YouTube tutorials. I tried booting into recovery mode and even spent time with Apple Care. My desk accumulated a few coffee mugs as I continued my search for answers.

Nothing worked, and I eventually gave up and went to bed, frustrated and without a solution.

The Morning Discovery

The next morning, after getting some sleep, I came across a thread mentioning hardware security keys. I glanced at my Yubikey still plugged into my Mac Mini's USB port.

I'd been using my Yubikey for months without issues. It had become such a seamless part of my setup that I'd forgotten it was even there.

I researched Yubikey issues and found mentions of PIN management lockouts. The symptoms matched perfectly: computer refusing login, PIN errors, all happening after I'd entered my PIN incorrectly too many times while trying to access system settings.

The Simple Solution

With a fresh perspective, I found an article explaining what was happening. It wasn't my Mac that was locked—it was my Yubikey's PIV PIN management system.

The solution? Simply unplug the Yubikey.

I pulled the small device from my USB port and tried logging into my Mac Mini again.

It worked immediately. No errors. No problems.

I was surprised how such a simple solution had eluded me during my late-night troubleshooting session.

The Fix

For anyone in a similar situation, here's what I learned: When your Yubikey's PIV PIN gets locked (which happens after multiple incorrect PIN entries), it can prevent your Mac from accepting your login credentials.

The fix is straightforward:

1. Unplug your Yubikey
2. Log in to your Mac (which should now work)
3. Follow the Yubikey PIN unblocking procedure outlined on SSL.com

The proper fix involves using the correct PUK (PIN Unblocking Key) to restore functionality to your Yubikey.

Lessons Learned

This experience taught me a few valuable lessons:

1. Start with the simplest explanation when troubleshooting
2. Don't forget about peripheral devices that might be affecting your system
3. Sometimes getting rest helps you see solutions more clearly

Technology has a way of creating unexpected problems with surprisingly simple solutions. Sometimes you just need to unplug something and plug it back in.