i want to register new templates through my plugin. Now if i execute my functions to add the new templates i get the error message Too few arguments to function register_plugin_templates(), 1 passed in .../current/web/wp/wp-includes/class-wp-hook.php on line 309 and exactly 3 expected.

It looks like a wordpress error or did i something wrong?

This is my code:


/** Template-Funktionen */
function get_plugin_templates(){
    $templates = [];
    $templates['dashboard'] = 'Dashboard Center';
    $templates['mein_account'] = 'Center - Mein Account';

    return $templates;

function register_plugin_templates( $page_templates, $theme, $post ){
    $plugin_templates = get_plugin_templates();

    foreach( $plugin_templates as $key => $value){
        $page_templates[$key] = $value;

    return $page_templates;

function include_plugin_templates($template){
    global $post;

    $page_template_slug = get_page_template_slug( $post->ID );
    $plugin_templates = get_plugin_templates();

    if( isset( $plugin_templates[$page_template_slug] ) ){
        $template = plugin_dir_path( __DIR__ ) . '/templates/' . $page_template_slug . '.php';

    return $template;


add_filter( 'theme_page_templates', __NAMESPACE__ . '\register_plugin_templates' );
add_filter( 'template_include', __NAMESPACE__ . '\include_plugin_templates' );

1 Answer 1


This is the problem, or rather what is missing from it:

add_filter( 'theme_page_templates', __NAMESPACE__ . '\register_plugin_templates' );

Specifically, you never told it that your function can accept 3 parameters, so it assumed it only accepts 1 as that's the absolute minimum needed for a filter to work. Then on top of that, none of your parameters are optional, they're required/mandatory. So PHP doesn't know what to do and generates an error.

Think of it this way:

If you were at a safe/vault and was told that to unlock it you had to place all 3 hands in the slots provided, what would you do? Most people have 2 hands, and others fewer, and you can't use somebody elses hand, so what are you supposed to do? It needs 3!

The official docs cover what parameters add_filter takes and what they do:

add_filter( string $hook_name, callable $callback, int $priority = 10, int $accepted_args = 1 ): true

Your code only provides the first 2, and doesn't define the priority or accepted arguments number.


  • Hey Tom, i understand. I hadn't seen it. Thank you.
    – Stefan
    Nov 28, 2022 at 13:36
  • if this answers your question, please consider marking it as the correct answer by clicking the tick button underneath the voting controls
    – Tom J Nowell
    Nov 28, 2022 at 15:22

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