Custom 404 - menu disappears

Question

I have created a custom 404 page using hook_preprocess_page():

function THEME_preprocess_page(&$variables) {
  $header = drupal_get_http_header('status');
  if($header == '404 Not Found') {
    $variables['theme_hook_suggestions'][] = 'page__404';
  }
}

The contents of page--404.tpl.php is identical to the contents of page.tpl.php except that use a static text block instead of calling print render($page['content']);. When this page is displayed one of the menus disappears from the header. Everything else look just as it does when I'm on a ordinary page except for the menu.

Since I only wan't to change the actual message that is displayed when receiving a 404 page and still use the rest of the markup contained in page.tpl.php perhaps it would be a better idea to only alter the $page['content'] inside a hook or similar?

Would appreciate if anyone could help me figure out why the menu is vanishing or could give me a solution that only alters the $page['content'] in page.tpl.php in case of a 404.

Answer 1

If you can accept using a module for this, rather than a theme override, you should be able to use CustomError:

This module allows the site admin to create custom error pages for HTTP status codes 403 (access denied) and 404 (not found), without the need to create nodes for each of them.

Just to make sure I've understood the use case: You write:

Since I only wan't to change the actual message that is displayed when receiving a 404 page

This message is by default "Page not found The requested page "..." could not be found. ". I think CustomError' will reproduce the standard message unless you override this - but it may something about your use case that I have not understood.

Answer 2

One option would be to update your THEME_preprocess_page function to initialise a custom boolean variable based on whether the page returns a 404.

function THEME_preprocess_page(&$variables) {
  $header = drupal_get_http_header('status');
  $variables['page']['page_not_found'] = false;
  if($header == '404 Not Found') {
    $variables['page']['page_not_found'] = true;
  }
}

You could then use this custom variable in your page.tpl.php (similar to how you check for $logo or $site_title) to display either the custom 404 text or $page['content'].

<?php if($page['page_not_found']): ?>
    <p>CUSTOM 404 TEXT</p>
<?php else: ?>
    <?php print render($page['content']); ?>
<?php endif; ?>

I would only recommend doing this if the 404 page contains only minor changes to a standard page. Otherwise, a different template file woild be the way to go.

Regarding the menu issue, I believe by default the primary links are hidden on 404 pages. This topic is discussed on drupal.org here, 'setvik' states the following solution:

To work-around the problem, do the following:

1) Create a custom node to handle "Page not found"'s.

2) go to Admin -> Site Configuration -> Error Reporting and set the "Default 404 (not found) page:" to the node you just created.

I can vouch for this as I've had to do it myself numerous times in the past.