Error since WP 3.9

Hello.

There’s an error when posting a comment.
mysql_query() and mysql_query_row() have been deprecated since WordPress 3.9.

Fix:
subscribe-to-comments-reloaded.php Line 945, replace this:

// Get the parent comment author email so we can search for any Replies Only subscriptions
$parent_comment_author_email_query = mysql_query( "SELECT <code>comment_author_email</code> FROM $wpdb->comments WHERE <code>comment_ID</code> = '$parent_comment_id'" );
$parent_comment_author_email       = mysql_fetch_row( $parent_comment_author_email_query );
$parent_comment_author_email       = "\_stcr@\_" . $parent_comment_author_email[0];

with this:

// Get the parent comment author email so we can search for any Replies Only subscriptions
$parent_comment_author_email = "\_stcr@\_" . get_comment_author_email( $parent_comment_id );

Cheers 🙂
Greg

https://wordpress.org/plugins/subscribe-to-comments-reloaded/