Error in custom php function doesn't exist

Question

I was able to successfully set the default page template for a new page, when there is not yet a defined template to be member_home_page.php.

This works perfectly on my local environment but when I uploaded the code to my site on WP Engine I get this error at the top of the admin page edit screen for WordPress.

Warning: call_user_func_array() expects parameter 1 to be a valid callback, function 'set_default_page_template' not found or invalid function name in /nas/content/staging/pmbus/wp-includes/class-wp-hook.php on line 288

Both on local and live deployments the function works. But on local I don't get the error, only live. Below is the function, i'm just not sure why i'm getting this warning only on live. Thanks in advance.

function set_page_template_default() {

    global $post;

    if ( 'page' == $post->post_type
        && 0 != count( get_page_templates( $post ) )
        && get_option( 'page_for_posts' ) != $post->ID // Not the page for listing posts
        && '' == $post->page_template // Only when page_template is not set
    ) {
        $post->page_template = 'member_home_page.php';
    }

}

add_action('add_meta_boxes', 'set_page_template_default', 1);

Answer 1

You get an error because it's looking for function named as set_default_page_template while you seems to have function named set_page_template_default.

I'm not sure you either don't have a function named set_default_page_template or you later renamed it. but that's the error. WP cannot find your hook because it doesn't exist.

you should either rename your set_default_page_template to set_default_page_template (if this is the function what you need) or you should create a new function and name it as set_default_page_template