Steve Day

As a followup, it looks like this change has already been added to the WP Dependency Installer Github repo and just needs to be ported into the plugin.

To the plugin author(s)

From a developer/tech standpoint, this appears to be a change to /wp-admin/includes/class-wp-upgrader-skin.php. The feedback function now has a spread operator as a 2nd parameter. See https://wptavern.com/coming-in-wordpress-5-3-what-is-the-php-spread-operator for more info on spread operators in WP 5.3.

A possible fix is to update the WP Dependency Installer class as follows:
/vendor/afragen/wp-dependency-installer/wp-dependency-installer.php line 530

FROM:
public function feedback( $string ) {}

TO:
public function feedback( $string, ...$args ) {}

I changed the code on my dev site and the warning went away. However I have not fully tested to see what the impact of this change is.

Follow up: Here’s some info from Andrew Nacin posted today (12/12/12) regarding this issue in 3.5. Apparently it is simply a warning. Nothing is technically broken and the plugin will function correctly. However, this could open the plugin up for injection issues. It should be fixed.

https://make.www.ads-software.com/core/2012/12/12/php-warning-missing-argument-2-for-wpdb-prepare/

Unfortunately I’m getting the same thing here. I did a vanilla install of WordPress 3.5 and added just that plugin to confirm there wasn’t anything else possibly conflicting.