MacOS error code -8058 Got this error while trying to copy &amp; paste a folder from my NAS to my Mac using Finder on MacOS 10.13.2:


  The operation can’t be completed because an unexpected error occurred
  (error code -8058).


Where are these mystery codes kept?  I tried google, tried the macerror utility in Terminal, tried osstatus.com, even tried searching opensource.apple.com - no luck.  Is there someplace to lookup Mac error codes?
Most of these codes are defined in the MacErrors.h header file. It might be that you need Xcode installed to have that header file on your system, so you can look it up online here:

https://opensource.apple.com/source/CarbonHeaders/CarbonHeaders-18.1/MacErrors.h

It lists a huge number of error codes with a short explanation.

Some error codes are not defined in this header file, but instead in other, similar header files for various subsystems. For example AppKitErrors.h, FoundationErrors.h, CoreDataErrors.h, etc.

Unfortunately your error code -8058 is not defined in MacErrors.h.