If we try to access a non-existant Multisite site, e.g., http://site1.example.com or http://example.com/site1/, we are redirected to http://example.com/wp-signup.php?new=site1.

How to block this and redirect the browser to another page?



An alternative (maybe better) is to use the following constant in wp-config.php:

define( 'NOBLOGREDIRECT', 'http://example.com' );

At the very beginning of wp-signup.php file there is this code:

function do_signup_header() {
    do_action( 'signup_header' );
add_action( 'wp_head', 'do_signup_header' );

So, it's just a matter of adding the signup_header action hook to break any further execution and redirect the browser to other URL.

Here, wrapped as a Must Use Plugin:

    Plugin Name: Multisite - Prevent Sign-up Page
    Plugin Url: http://wordpress.stackexchange.com/q/85529/12615
    Version: 1.0
    Author: Rodolfo Buaiz

add_action( 'signup_header', 'rbz_prevent_multisite_signup' );

function rbz_prevent_multisite_signup() 
    wp_redirect( site_url() );
  • 1
    @kaiser, always disliked this behavior in closed networks ;) – brasofilo Feb 13 '13 at 12:18
  • hey, unser @kaiser, there's a better alternative, IMO. Updated the A with it. Also published a related one. – brasofilo May 3 '13 at 1:18
  • I just wanted to state that I dislike the core behavior. In the meanwhile I found the regarding DropIns, when I talked about them. +1 on both answers. – kaiser May 3 '13 at 10:12
  • 1
    Was messing around a lot with function to prevent redirects and .htaccess to recognize */wp-signup.php to redirect to the network home page. The define( 'NOBLOGREDIRECT', %URL% ); finally solved it! +1 (noteworthy: result not necessarily visible on localhost with custom URL redirect using Windows hosts file) – rkeet Oct 20 '14 at 13:42
  • 1
    This is incorrect - the hook used should be before_signup_header, not signup_header. otherwise you receive 'Headers already sent' errors. – Mark Jul 30 '17 at 8:55

I found a solution in this article

I had the wrong SUBDOMAIN_INSTALL setting value in my config file.

  • A link-only answer will become invalid with a dead link. Would you please edit and elaborate your answer in brief and then provide the link for additional information? – Mayeenul Islam Nov 30 '14 at 5:03

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