Laravel 5.5 has been available for about a week now and if you have been using Laravel for quite some time you are probably familiar with using the Laravel Installer command:

laravel new blog

I was excited to use Laravel 5.5 and had already ran that command a few times, and I ran into a few problems/errors when running the command. One of which was:

You made a reference to a non-existent script @php -r "file_exists('.env') || copy('.env.example', '.env');"

And the second one was:

[InvalidArgumentException]
Script "post-install-cmd" is not defined in this package

In case someone runs into this same problem, I wanted to share the simple solution.

The first issue was resolved by updating my version of composer:

composer self-update

And the second one was to upgrade my version of the Laravel Installer:

composer global require "laravel/installer"

After running those two commands I'm able to execute my laravel new command like usual!

Hope this helps someone else in need.