I had the same problem, which I’ve tracked down to this line in the domain_mapping.php file:
null == $wpdb->get_var( $wpdb->prepare( "SELECT domain FROM {$wpdb->dmtable} WHERE blog_id != %d AND domain = %s", $_POST[ 'blog_id' ], $domain ) )
Which seems to be checking that the map doesn’t already exist, but if we’re editing the map then it will!
The line below:
$_POST[ 'orig_domain' ] == ''
seems to have the same function (which then decides whether to INSERT or UPDATE).
So I’m not sure we need first null ==
condition.
I’ve removed that condition and the map now updates. And everything seems to work ok.
But it would be good to know if I’ve just broken the plugin somehow?
Thanks, Peter