Fix AJAX bug created by web hosts who inject ads into html pages

[palotasb]

Most web hosting companies insert ads into HTML pages downloaded from them. This breaks some admin page features, because files downloaded via AJAX have a text/html header and the host automatically injects the ads. This sometimes creates a reload cycle or makes the page completely unaccessible.

I have fixed the issue partly by editing /wp-admin/admin-ajax.php at line 19 and /wp-admin/index-extra.php at line 18, by overwriting the Content-Type header to be text/plain. This does not fix the issue on the admin dashboard, where some widgets need to be disabled.

I suggest that any content not rendered directly by the browser (used for AJAX data transfer only, processed by JavaScript, where only content matters) should be transferred using a text/plain header. This should be a straightforward change and I don't think it could cause any bugs (actually, it works for me), but you may want to investigate.

In case you want to reproduce, you have to set up a web server in a way that it injects some content into the body of every served file with the text/html MIME type.

[Denis-de-Bernardy]

Most web hosting companies insert ads into HTML pages downloaded from them.

That sounds so 1995... I haven't run into a hosting company that does this in *ages*.

Suggesting we close this as wontfix.

@palotasb: If you need free WP hosting, consider using wordpress.com. If you need to host WP yourself, several cheap hosts are highlighted on wordpress.org.

[filosofo]

That's pretty ridiculous. Like Denis said, if you need free or cheap hosting, there are better options.

Since this is such an obscure problem, it's really just plugin material:

function my_text_header() {

   if ( is_defined('DOING_AJAX') && DOING_AJAX  ) {
     @header('Content-Type: text/plain; charset=' . get_option('blog_charset'));
   }
}

add_action('admin_init', 'my_text_header');