I’ve got the same problem and have traced it a little further. I think it has to do with deleted users in general and not just the first user. The problem appears to be in core.
/wp-includes/author-template.php – line 73:
$last_user = get_userdata($last_id);
In my case $last_id is 4 which is a user that was deleted. The next line never checks if get_userdata() returns false and blindly uses a property on it. I’ve patched my local install by adding this to the CMS TPV functions file and changing line 1246 to use it instead.
function cms_tpv_get_the_modified_author() {
if ( $last_id = get_post_meta( get_post()->ID, '_edit_last', true) ) {
$last_user = get_userdata($last_id);
if( $last_user !== false ){
return apply_filters('the_modified_author', $last_user->display_name);
}
}
}
