Here we will answer on frequently asked questions.
1. LESSC compiler is not available on path
Curently, due to historical reasons we still use Less CSS for some of our stylesheets. It was default stylesheets compiler for Odoo versions <= 11.0. After Odoo 12.0 released, the default stylesheet compiler is Sass Lang (SCSS), but old Less CSS is still supported by Odoo. The only inconvenient thing is that Less CSS after Odoo 12.0 is not installed by default, so you have to install it manually.
To Install Less CSS, you can use installation instruction for Odoo 11.0 (look for Less CSS via nodejs section). The content of this section is below:
on Linux, use your distribution’s package manager to install nodejs and npm.
Once npm is installed, use it to install less:
on Windows, install nodejs, reboot (to update the
PATH) and install less:
Also, if you use CRND Deploy project to install Odoo, then you will get Less CSS (and other dependencies) installed automatically.