can't download from composer on linux OS

Question

Problem 1
    - Installation request for kreait/firebase-php 4.35 -> satisfiable by kreait/firebase-php[4.35.0].
    - kreait/firebase-php 4.35.0 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.

You can also run php --ini inside terminal to see which files are used by PHP in CLI mode.

Answer 1

The error is asking you to install the module mbstring if you are using ubuntu

try this

sudo apt-get install php-mbstring