I got these errors when activating the plugin:

Warning: in_array() expects parameter 2 to be array, boolean given in /home1/xxx/public_html/sites/wp-content/plugins/gr-order-category-post/gr-order-category-post.php on line 28
Warning: Cannot modify header information – headers already sent by (output started at /home1/hlr/public_html/sites/wp-content/plugins/gr-order-category-post/gr-order-category-post.php:28) in /home1/xx/public_html/sites/wp-admin/includes/misc.php on line 1116