WordPress query undefined offset in loop

I created a query with arguments see blow.
On the page I see an error in a loop

• Notice undefined offset 1
• Notice undefined offset 2
• Notice undefined offset 3 and so on…

  $args = array (
    'post_type'     => 'catalog',
    'post_status'   => 'publish',
  );
  $loop = new WP_Query( $args );
     if ( $loop->have_posts() ) {
        while ( $loop->have_posts() ) {
            the_post(); 
            echo get_the_title();
        }
    }

I tried other arguments but this does not work.

• ‘posts_per_page’ => 4

Please who can help me?

Answers:

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Method 1

There might be other causes to the issue in question, but one issue I noticed in your code is that because you are looping through a custom WP_Query instance, i.e. $loop, then you need to use $loop->the_post() instead of just the_post():

while ( $loop->have_posts() ) {
    $loop->the_post();
    the_title();
}

And you could see that I simply called the_title() and not doing echo get_the_title(), so you should also do the same.

Method 2

There are five default Post Types readily available to users or internally used by the WordPress installation:

1. Post (Post Type: ‘post’)
2. Page (Post Type: ‘page’)
3. Attachment (Post Type: ‘attachment’)
4. Revision (Post Type: ‘revision’)
5. Navigation menu (Post Type: ‘nav_menu_item’)

refer this link for more: https://developer.wordpress.org/themes/basics/post-types/
according to me your post type in the query is wrong.
use post_type => 'post'
instead of post_type => 'catalog'

$args = array (
  'post_type'     => 'post',
  'post_status'   => 'publish',
);
query_posts($args); 
                if(have_posts()) {
                    while(have_posts()) {
                        the_post();
                        echo get_the_title();
                           }
                     }

Please correct it if you find it correct.

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0