Pamps

Much is made of the WordPress function wp_get_attachment_image_src() which returns an array of data for an attachment image.
But dealing with the array is not alway welcome.

wp_get_attachment_image_url() is your friend here as it returns the URL of the attachment at the desired size.

Pamps

#$ cat fix-dropbox.sh 
#!/bin/bash

# XXX: use at your own risk - do not run without understanding this first!
#exit 1

# safety directory
BACKUP='/tmp/fix-dropbox/'

# TODO: detect or pick manually...

Pamps

<?php

// Change the image size used for the WooCommerce product gallery image zoom
// 'medium' or 'large' are normally the best options
add_filter( 'woocommerce_gallery_full_size', function( $size ) {
    return 'medium';
} );

?>