SEARCH QUERY PLEASE HELP | call_user_func_array() expects parameter 1 to be a valid callback php

You have extra spaces around change_posts_order, inside the quotes:

add_action( 'pre_get_posts', ' change_posts_order ' );

PHP can’t find a function with that name, because wits looking for that function preceded with the spaces. Remove the spaces to fix the issue:

add_action( 'pre_get_posts', 'change_posts_order' );

Related Posts:

  1. Best practice custom function, where to echo the variables?
  2. How to delete taxonomy term when a wordpress user is removed?
  3. How to filter, restrict and return posts based on custom user meta information
  4. Is it possible to completely stop WP_Query retrieving posts?
  5. Hook/action after WP_Query gets posts to query custom tables for post-related meta
  6. ajax category filter
  7. WordPress 4.9.5 PHP intermittent warning trim() expects parameter 1 to be string, array given
  8. Want to redirect if search query match exact title of any post
  9. Overriding The Loop with filter or hook
  10. new WP_Query() – what is the earliest valid hook?
  11. Identify which loop you are hooking into; primary or secondary?
  12. Pagination custom query
  13. Order by two meta keys
  14. Finding all results from database within 500 miles of the given latitude and longitude [closed]
  15. Function to check if author has posted within the last x days
  16. Shortcode returns escaped HTML tags
  17. Calling a custom excerpt function in a local loop
  18. How to get any tag ID
  19. Dynamically Override Fancy Title – Part II
  20. query posts in functions.php and update a field
  21. Get posts using WP_Query
  22. Finding post content that begins with a specific character
  23. How to get user_id from wordpress database inside ajax function?
  24. Gravity Forms field entries into wp_query loop [closed]
  25. How to change posts order on Category and Tag archives?
  26. posts_per_page not working
  27. is_search was called incorrectly
  28. Exclude admin from WP_Query Contributors
  29. Multiple Loops Inside a Function
  30. How to choose between hooking into per_get_posts or into parse_query
  31. How to use filter hook “the_posts” with a function that refers to $this?
  32. Exclude category for main query and custom
  33. Display posts from only one post form in custom query and exclude in main query
  34. Category applied to pages, creates multiple breadcrumb entries after a search query (On the translated site)
  35. How to use the query hook/filter?
  36. WP Query using tax_query & meta_query
  37. Set global $wp_query/$post variable for dynamic page generation
  38. wordpress search word, “hello world” ===> ‘hello+world’ ===> ‘hello’, ‘world’
  39. Display most popular in the past two days
  40. meta_query not working as expected
  41. New WP_Query calls Pre_get_posts filter twice
  42. how to access query string in wordpress?
  43. How can I override one post and make it display content for another post?
  44. Merge two search functions for custom post type
  45. Make a SQL query with wpdb in WordPress
  46. how to use pre_gets_posts to exclude one queried ID from homepage loop
  47. Error with function in functions.php?
  48. queried_object using pre_get_posts gets notices and warning
  49. Utilising an existing page while using the “s” query parameter
  50. Exclude authors IDs from WP_Query
  51. Loading two different AJAX requests on two different pages
  52. Getting the post terms ‘wp_get_post_terms’ per post when within the functions.php file
  53. How to load a script code only in posts?
  54. Multiple meta_key ordering with pre_get_posts
  55. How do I fit WP_Query arguments into a function?
  56. Create a notification for post field
  57. Add URL Rewrite Rule To WordPress
  58. Trying to get property of non-object in: $wp_query
  59. WordPress dynamic AJAX query
  60. relation OR instead of AND – Filtered term ID’s in loop
  61. Filter for replacing the WP_query object for a given category
  62. Elementor posts custom query based on tag [closed]
  63. WP_Query retuning empty array in rest api
  64. Pagination repeating posts on search results
  65. How to check if logged in user have pending custom post?
  66. Custom WordPress post query for displaying time-released content on website
  67. Custom query for custom post type not getting correct post ID
  68. Finding post ID dynamically on click
  69. how to move a page from one drop down menu to another drop down menu
  70. How to upload 3 attachments to current post?
  71. remove_action – pre_get_posts – does not restore original query
  72. Global page ID variable empty error
  73. WP_Query & shortcode : Return 3 articles from a category WordPress
  74. Get post Number with local loop and template
  75. Save query in function for custom gallery
  76. Seach and categories not working when ignoring sticky posts in main loop
  77. Problem with custom WP_Query and underlying pagination/posts_per_page
  78. Calling a function with WP_Query only ever brings the first result
  79. What argument does my function need to echo get_results() query results
  80. Rewrite rule pagination on different url levels
  81. Fetching $_POST from Page Template into functions.php
  82. Declare inline background image in functions.php
  83. I wan to process the following js to process the AJAX Request on my function to calculate author Total Post views
  84. Hiding all posts/products/pages from a site based on a custom taxonomy/domain name
  85. ordering and optimizing functions
  86. $wp_query when new WP_Query
  87. Why WP_Query in functions.php is not working when get_posts works?
  88. Adding css tweak based on page template
  89. WP_Query and DES sort for Custom Taxonomy based upon a meta field?
  90. How to write a query-function as a query-shortcode?
  91. 1500+ duplicate queries via get_option function (query monitor)
  92. Variations as Single Products [closed]
  93. Excluding a category from frontpage but not from WP_Query
  94. Prevent WordPress loop from displaying similar post titles
  95. Custom WordPress loop, articles not in same order as Array
  96. Group By query based on Custom Field
  97. delete_term is not working properly with add_action()
  98. Limit paginated result set to a maximum number of posts
  99. Custom query with custom filtering returning incorrect results
  100. Best performance for use Custom Field in WP