macOS Big Sur YubiKey Login Freezing

Question

Issue

After upgrading to macOS Big Sur's update on 11/19/20, the login screen freezes intermittently, after entering the YubiKey login pin, requiring the MacBook Pro to be shut down completely and turned on again.

The YubiKey issue has been documented from a few sources.

• Reddit - MacOS Big Sur SmartCard Authentication issues
• Apple Discussions
  • Stuck at lock screen, macOS Big Sur
  • Big Sur and smart cards

MacBook Pro Configuration

• Two-Factor authentication enabled with a YubiKey 5C
• OS: macOS Big Sur, Version 11.0.1
• Device: MacBook Pro (15-inch, 2019)
• Processor: 2.3 GHz 8-Core Intel Core i9
• Memory: 32 GB 2400 MHz DDR4

Attempted Solutions

1. Restart the computer.
2. Shutdown and turn back on.
3. Reset NVRAM. See: Reset NVRAM or PRAM on your Mac
4. Reset SMC. See: How to reset the SMC of your Mac
5. Run Disk Utility's First Aid: No issues found
6. Run Apple Diagnostics: No issues found
7. Scan computer with AVG Antivirus: No viruses found
8. Reinstall Big Sur from macOS Recovery
9. Remove apps from starting automatically at login. Specifically, there was a Zoom app that I removed from starting at login. See: Add or remove automatic items
10. Run in safe mode: The frozen login screen still persists intermittently in safe mode. See: How to use safe mode on your Mac

Answer 1

Performing a factory reset and restoring the system from a Time Machine backup has resolved the login freezing issue with Yubikey's Yubico 5C.

The Time Machine backup restored to the Mac was created right before doing the factory reset.