MacOS 10.8.5 Error 102

Mid 2017 Airs can run the latest macOS, Big Sur.

You can try simply updating with this How to upgrade to macOS Big Sur - Apple Support

If it doesn't work, I'd advise you to make a clean install of macOS.

First backup your personal data to an external USB drive.

Now create a bootable USB installer following this How to create a bootable installer for macOS - Apple Support

Restart holding Option and choose the USB installer

Once Recovery Mode is loaded, open Disk Utility and completely erase the internal drive

Close DU and proceed installation.

That I consider the best way because you'll have a clean install, free from debris from old versions like system files and settings that could cause you some trouble.

Hardware Overview:

  Model Name: Mac mini

  Model Identifier: Macmini6,1

  Processor Name: Dual-Core Intel Core i5

  Processor Speed: 2.5 GHz

  Number of Processors: 1

  Total Number of Cores: 2

  L2 Cache (per Core): 256 KB

  L3 Cache: 3 MB

  Hyper-Threading Technology: Enabled

  Memory: 4 GB

  Boot ROM Version: 421.0.0.0.0

  SMC Version (system): 2.7f0

  Serial Number (system): C07K631EDWYL

  Hardware UUID: F9F1D18E-19D3-5080-9E9E-C78E0A939EAB

• Since I upgraded to Catalina 10.15.7 my Mac mini could not recognize my VERBATIM external storage. Consequently I could not transfer my files saved in the VERBATIM back to my Mac mini. PLEASE, HELP me solve this problem.

What is your Mac model and year?