The file wp-admin/includes/plugin.php is not always included. You may have to do this in your plugin.
And your Location header is invalid: You have to send a complete URL.
You should use:
require_once( ABSPATH . 'wp-admin/includes/plugin.php' );
When do you call this function? Maybe too early.
Related Posts:
- How to include PHP files in plugins the correct way
- How can you check if you are in a particular page in the WP Admin section? For example how can I check if I am in the Users > Your Profile page?
- Why does WordPress add 0 (zero) to an Ajax response?
- Passing arguments to a admin menu page callback?
- What is an alternative method to the WordPress private _doing_it_wrong() function
- Understanding WordPress functions’ naming conventions
- Using OOP plugin’s methods throughout the website
- function triggered by “manage_users_custom_column” filter not working
- How can I change the frequency of a scheduled event?
- WordPress plugin how to run function when button is clicked
- When is it appropriate to put functions on page template vs. functions.php?
- Shortcodes, output buffering, and WordPress functions
- Determine which theme location a wp_get_nav_menu_items is for
- When to check if a function exists
- Checking for existence of a page by title?
- Problems with removing admin bar
- Problem with `wp_mail()`
- Calling a function from functions.php in custom page/ blog post
- Check if I am in the Admin Panel (wp-admin)?
- What is the difference between current_page_parent and current_page_ancestor?
- Plugin development: is adding empty index.php files necessary?
- Does add_filter work outside functions.php
- What function to hook for changes made in status and visibility of a post
- how to use preg_replace for wordpress video?
- Plugin Uninstall and Deactivate via Options Menu
- wp_enqueue_script + wp_enqueue_style Since When
- Widget update function not saving values
- add more custom post types and custom role to the code
- $content variable – Is this a reserved variable for a WordPress function? – php / wordpress
- How to use WP_Term with (menu) argument in the wp_nav_menu?
- WordPress after content Hook & external template part
- Enqueue scripts in footer
- override pluggable.php functions
- Retrieve contents/page names of various pages for use in a plugin
- Can wp_list_comments output into variable?
- is user logged in not working
- Can I change header.php of current theme through a plugin function?
- get_current_screen() return null
- Override class inside $atts shortcode_atts in WordPress
- creating custom function to log actions in plugin
- Maximum lifetime for nonce
- Adding option to Gallery shortcode
- correct way to call javascript into hook function
- How to change the hover content of a specific menu item on WordPress?
- how to search users by ajax live search
- Remove unwanted elements for a wp_nav_menu
- How do I update a field of a meta box?
- How to add user details to different tables immediately after user registration
- WordPress function get_the_terms() returns ‘Invalid taxonomy’ error
- WordPress class, using add_action to call member function does not work
- How to modify files inside wp-includes directory in wordpress
- Fatal error: Call to a member function get_page_permastruct() on a non-object
- wp_get_post_terms Order by not working
- Function/Class to list categories with checkboxes
- wp_get_theme Warning: Illegal offset type
- Why wp_die() doesn’t work with wp_redirect but exit() works
- Warning: call_user_func_array() expects parameter 1 to be a valid callback
- Print Dashboard submenu name and filename
- Alternative functions for mysql_free_result and mysql_ping in wordpress functions
- Apply styles to blockquote element with the WYSIWYG editor
- Call to undefined function is_home() or any conditional tags
- How to change WooCommerce loop product title HTML output in single product page and archive page
- How to output functions from plugin inside theme
- wp_schedule_event is registered but function isn’t running
- Overwriting a plugin function
- Writing editor content to a file
- Remove Permalink Meta Box not working?
- Adding tables to dashboard pages programmatically?
- Setting post_id for single.php based on URL without a redirect
- using admin functions on frontend
- Javascript Function Called Too Early in PHP Script
- Modify code for functions.php with specific twitter user url and hashtags
- can’t access some WordPress function from my plugin
- Custom Settings Plugin Save foreach checkboxes
- Customise Grouped Product display in Woocommerce with custom column
- Change the behaviour of a button
- Can someone explain what’s the use of parse request function in WordPress?
- Add default value from selection
- function add custom fields to media gallery
- Override category archive page title (not the head title)
- Make visible page only in the trash
- Redirection from a specific page for users logged in but not with membership
- Why would one specify multiple arguments when using get_previous_posts_link() which takes only one parameter?
- I cant add is_admin control to plugin
- Does hooking into a plugin action / filter override the plugin’s function for that hook?
- WordPress plugin how to run function when button is clicked
- wp_ajax add_action fuction won’t fire on custom jQuery action
- Add function to Dokan ajax class
- foreach argument to get specific file types getting too many returns
- Function not working on any file other than the main plugin file
- Building WordPress Themes With Bootstrap with Adi Purdila → TutsPlus
- Template file structure , wordpress hook for altering the template
- WordPress permalink setting
- How can I see a varibles value when my plugin runs?
- Dynamic banner for use on external sites
- How can i call from custom fields to the category editor?
- Custom options page for themes
- Why does this fail: Disabling plugins enqueue_script() in functions.php
- Call do_action() within WordPress cronjob
- get_term_by() returning null on plugin