With STORM any new site that you add to your server will have the PHP's open base directory restriction enabled by default.
open_basedir is a security module for PHP that sets the folder paths that your website is allowed to read and write to. Typically you would only want your website to be able to read/write to files and folders from within the sites document root. This is useful from a security point of view as if your site becomes compromised and tries to alter folders & files on another site on your server, open_basedir will stop this. In addition to open_basedir STORM also runs PHP as a different user for each website to again prevent one site from being able to alter folders & files on another site on your server.
To check that open_basedir is enabled on your site you can follow the below steps
From the STORM dashboard, click on the cog icon next to your website to manage the hosting for that website.
Click on PHP
At the bottom of the page you can see a list of PHP directives. Check to make sure you have one called open_basedir