Pagination 404 on Index with custom query

Question

On my wordpress index, I use a custom query:

$paged = (get_query_var('page')) ? get_query_var('page') : 1;

$project_query = new WP_query(array(
  'post_type' => 'project',
  'paged' => $paged,
  'posts_per_page' => 5
));

I am using wp-paginate to setup page numbering, but regardless, as soon as I try to go to the next page, eg: http://domain/page/2 I get a 404 error.

I really cannot for the life of me figure out what is happening. I've set the wordpress reading option to the same number, and my permalink structure is set to Post name.

Any tips greatly appreciated, I know pagination 404's are a common issue with a lot of people but I haven't been able to find someone who had the same issue with the index.

Answer 1

whether or not a page exists or results in a 404 is decided based on the results of the main query, which happens before the template is loaded. WordPress isn't "aware" of your custom query, it's separate from the main query and happens only if the main query results in the loading of the template which contains it.

instead of creating this custom query, you can modify the main query before it is sent to the database via the pre_get_posts action. this code would go in your theme's functions.php file:

function wpa_front_page_projects( $query ) {
    if ( $query->is_front_page() && $query->is_main_query() ) {
        $query->set( 'post_type', array( 'project' ) );
        $query->set( 'posts_per_page', 5 );
    }
}
add_action( 'pre_get_posts', 'wpa_front_page_projects' );