How to turn off searching from URL and go straight to 404 page

Question

When I put something after my domain name that doesn't exist I am taken to my 404 page, for example:

example.com/sdkjhfdsjk

But if I put something that exists as an image I am taken to the page for that, for example:

example.com/imagename

How can I turn this off. I only want to be taken to pages or posts that exist.

UPDATE: This has been marked as a duplicate but the accepted answer to that does NOT fix this.

I added:

remove_action('template_redirect', 'redirect_canonical');

to my themes functions.php but the same action happens.

Answer 1

Try

function no_attachment_page() {
  global $wp_query;
  if ( $wp_query->is_attachment()  ) {
    $wp_query->set_404();
    status_header(404);
    nocache_headers();
  }
}

add_action( 'template_redirect', 'no_attachment_page', 1 );

This should result in a 404 everytime you try to access to an attachment page.