When I open the terminal shows “The specified command(“completion”) is invalid. For a list of available options, run “ng help”

I had the same error after updating angular every time after opening the terminal.

Depending on which terminal you use either open configuration file which will be saved in ~/.bashrc, or for zshell ~/.zshrc, and so on for others,

Edit the corresponding ~/.bashrc or ~/.zshrc file and delete or comment this line:

source <(ng completion script)

Sadly you will lose the angular autocompletion, but it looks like there is some bug causing this in their implementation