How can I get something like this to work?

// in a plugin / theme:
// This imaginary function will make WordPress think that the 
// current request is a 404. 
// Ideally this function could be ran anywhere, but realistically it
// will probably have to be before the template_redirect hook runs.
generate_404_somehow();

// later...
add_action('template_redirect', function() {
    // should be "true"
    var_dump(is_404());
});

Basically under certain conditions, I want to tell WordPress to show its 404 template (which I can hook into later if I want) instead of the template it's about to load (eg a page or archive).

I know I could just do a 302 redirect to a non-existent page but that's very messy. I could also send a 404 HTTP header manually, but then I can't use WP's nice 404 page (I already have things that hook into is_404() that need to get fired at the right time).

How can I get something like this to work?

// in a plugin / theme:
// This imaginary function will make WordPress think that the 
// current request is a 404. 
// Ideally this function could be ran anywhere, but realistically it
// will probably have to be before the template_redirect hook runs.
generate_404_somehow();

// later...
add_action('template_redirect', function() {
    // should be "true"
    var_dump(is_404());
});

Basically under certain conditions, I want to tell WordPress to show its 404 template (which I can hook into later if I want) instead of the template it's about to load (eg a page or archive).

I know I could just do a 302 redirect to a non-existent page but that's very messy. I could also send a 404 HTTP header manually, but then I can't use WP's nice 404 page (I already have things that hook into is_404() that need to get fired at the right time).

• redirect
• 404-error

Share Improve this question edited Nov 23, 2012 at 14:37 dave1010 asked Nov 23, 2012 at 14:23 dave1010dave1010 19311 gold badge11 silver badge66 bronze badges 5

• Perhaps I could modify the query to search for a non-existent page. – dave1010 Commented Nov 23, 2012 at 14:24
• Can you clarify the question here? Are you trying to run code on your theme's 404 page or do you intentionally want to create a 404 error? – Steve Commented Nov 23, 2012 at 14:32
• I want to create a 404. I'll edit the question a bit... – dave1010 Commented Nov 23, 2012 at 14:32
• in which case/when and why do you want to generate a 404 page? – fischi Commented Nov 23, 2012 at 15:45
• I've needed to do this on at least 2 different occasions. Most recently was making legacy author pages give a 404. It's also something that I'm sure I'll need again in the future. – dave1010 Commented Nov 26, 2012 at 10:24

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3 Answers 3

Sorted by: Reset to default 8

function generate_404_somehow() {
   global $wp_query;
   $wp_query->is_404 = true;
}
add_action('wp','generate_404_somehow');

Of course, that will send all of you page to the 404 template. I don't know what the conditions are that this should fire or not fire.

Or to be more cautious (see comments) ...

function generate_404_somehow() {
   global $wp_query;
   $wp_query->set_404();
}
add_action('wp','generate_404_somehow');

The other by s_ha_dum answers doesn't set the HTTP Header Status to 404 Not Found. To do this adds status_header( 404 ) to the function.

function generate_404_somehow() {
    global $wp_query;
    $wp_query->set_404();
    status_header( 404 );
}
add_action('wp','generate_404_somehow');

• WordPress Code Reference: status_header()
• MDN web doc: 404 not found

What seems to work:

global $wp_query;
$wp_query->set_404();
$wp_query->max_num_pages = 0; // stop theme from showing Next/Prev links

This seems to set the HTTP headers and load the right template (with is_404() being true).