We ran into an issue yesterday when installing a new instance of X, the most recent version at the time of this writing. After searching, we came across an old thread that was exactly the problem, and hinted at a solution.
The error we keep getting when installing is “Your WordPress file permissions do not allow plugins to be installed.”
This error persisted even when we we changed all file and directory permissions in the install to 777.
It took a full day of searching and diagnosing, but the fix is to:
Edit wp-config.php and add define(‘FS_METHOD’,‘direct’);
Without this directive, X will continue to fail to install and it’s virtually impossible to debug why. This error could be more clear. This obviously isn’t a file permissions issue and leads a person in the wrong direction when diagnosing. You may want to consider a better algorithm that helps people when its one situation and not the other, or inform them that if they don’t want to use the FS_METHOD to add FTP credentials in some place. This is a nightmare for those who use SSH to manage the site.
Environment is Ubuntu 16.04, PHP 7.