Why isn't the vendor folder created in laravel?

Question

Composer

Installed laravel to real north with this command

composer create-project --prefer-dist laravel/laravel blog

, registered the path to the public/index.php file, and I go to the site, and there is an error

HTTP ERROR 500

, went to the console and registered the command:

tail -f /var/log/apache2/error.log

and that's what it showed

. So I understand that there is no vendor folder, it really doesn't exist, it wasn't installed for some reason, why?
I ran the composer update command and this is what it shows:
and I ran the composer self-update command, it says that there is no such command.

Answer 1

Install the mbstring extension for PHP.