New OS 14.1, disk first aid freezes drive

On some machines, (e.g. my 2014 MacBook Air), a Disk First Aid on the internal Mojave 10.14.1 APFS drive (128 GB) does not appear to have any progress for nearly 20 minutes — until just before it normally finishes. If you are an impatient individual, this may feel like a hung machine.

You have something that is corrupted. Even possibly you have a failing SSD. My suggestion is as follows:

1. Backup all your files.
2. Erase the SSD.
3. Reinstall macOS.
4. Restore your files.
5. Reinstall 3rd party software from the original media.

Internet/Network Recovery of El Capitan or Later on a Clean Disk

If possible back up your files before proceeding.

1. Restart the computer. Immediately after the chime hold down the (Command-Option-R) keys until a globe appears.
2. The Utility Menu will appear in from 5-20 minutes. Be patient.
3. Select Disk Utility and click on the Continue button.
4. When Disk Utility loads select the drive (usually, the out-dented entry) from the side list.
5. Click on the Erase tab in Disk Utility's main window. A panel will drop down.
6. Set the partition scheme to GUID.
7. Set the Format type to APFS (SSDs only) or Mac OS Extended (Journaled.)
8. Click on the Apply button, then click on the Done button when it activates.
9. Quit Disk Utility and return to the Utility Menu.
10. Select Reinstall OS X and click on the Continue button.

Note:

1. To install the version of OS X that was currently installed use Command-Option-R.

2. To install the original factory version when the computer was new use Command-Option-Shift-R.

I usually coordinate a First Aid run with a trip to the kitchen for a mug of dark roast. Then I use my other Mac while waiting for that eternal First Aid to complete.