How to fix 'ng upgrade' error 'The specified command ("upgrade") is invalid'

Problem:

You want to run ng upgrade to update your angular project libraries, but you see this error message:

The specified command ("upgrade") is invalid. For a list of available options,
run "ng help".

Did you mean "update"?

You need to run

ng update

instead of ng upgrade (which is not a valid command).

This is what Did you mean "update"? in the error message is intended to point you towards.