Title: MU | Page 2 of 6 | Developer.WordPress.org --- # New and updated in MU Functions Hooks Classes Methods * hook[mu_rightnow_end](https://developer.wordpress.org/reference/hooks/mu_rightnow_end/) * Fires at the end of the ‘Right Now’ widget in the Network Admin dashboard. * Used by [1 function](https://developer.wordpress.org/reference/hooks/mu_rightnow_end/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/hooks/mu_rightnow_end/#uses) | Source: [wp-admin/includes/dashboard.php:530](https://github.com/WordPress/wordpress-develop/blob/7.0/src/wp-admin/includes/dashboard.php#L530-L530) * hook[mu_activity_box_end](https://developer.wordpress.org/reference/hooks/mu_activity_box_end/) * Fires at the end of the ‘Right Now’ widget in the Network Admin dashboard. * Used by [1 function](https://developer.wordpress.org/reference/hooks/mu_activity_box_end/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/hooks/mu_activity_box_end/#uses) | Source: [wp-admin/includes/dashboard.php:537](https://github.com/WordPress/wordpress-develop/blob/7.0/src/wp-admin/includes/dashboard.php#L537-L537) * hook[wpmu_blogs_columns](https://developer.wordpress.org/reference/hooks/wpmu_blogs_columns/) * Filters the displayed site columns in Sites list table. * Used by [1 function](https://developer.wordpress.org/reference/hooks/wpmu_blogs_columns/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/hooks/wpmu_blogs_columns/#uses) | Source: [wp-admin/includes/class-wp-ms-sites-list-table.php:404](https://github.com/WordPress/wordpress-develop/blob/7.0/src/wp-admin/includes/class-wp-ms-sites-list-table.php#L404-L404) * hook[wpmublogsaction](https://developer.wordpress.org/reference/hooks/wpmublogsaction/) * Fires inside the auxiliary ‘Actions’ column of the Sites list table. * Used by [1 function](https://developer.wordpress.org/reference/hooks/wpmublogsaction/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/hooks/wpmublogsaction/#uses) | Source: [wp-admin/includes/class-wp-ms-sites-list-table.php:608](https://github.com/WordPress/wordpress-develop/blob/7.0/src/wp-admin/includes/class-wp-ms-sites-list-table.php#L608-L608) * hook[do_mu_upgrade](https://developer.wordpress.org/reference/hooks/do_mu_upgrade/) * Filters whether to attempt to perform the multisite DB upgrade routine. * Used by [0 functions](https://developer.wordpress.org/reference/hooks/do_mu_upgrade/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/hooks/do_mu_upgrade/#uses) | Source: [wp-admin/admin.php:74](https://github.com/WordPress/wordpress-develop/blob/7.0/src/wp-admin/admin.php#L74-L74) * hook[activate_blog](https://developer.wordpress.org/reference/hooks/activate_blog/) * Fires after a network site has its deletion flag removed. * Used by [0 functions](https://developer.wordpress.org/reference/hooks/activate_blog/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/hooks/activate_blog/#uses) | Source: [wp-admin/network/sites.php:294](https://github.com/WordPress/wordpress-develop/blob/7.0/src/wp-admin/network/sites.php#L294-L294) * hook[deactivate_blog](https://developer.wordpress.org/reference/hooks/deactivate_blog/) * Fires before a network site is flagged for deletion. * Used by [0 functions](https://developer.wordpress.org/reference/hooks/deactivate_blog/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/hooks/deactivate_blog/#uses) | Source: [wp-admin/network/sites.php:305](https://github.com/WordPress/wordpress-develop/blob/7.0/src/wp-admin/network/sites.php#L305-L305) * hook[wpmu_upgrade_page](https://developer.wordpress.org/reference/hooks/wpmu_upgrade_page/) * Fires before the footer on the network upgrade screen. * Used by [0 functions](https://developer.wordpress.org/reference/hooks/wpmu_upgrade_page/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/hooks/wpmu_upgrade_page/#uses) | Source: [wp-admin/network/upgrade.php:153](https://github.com/WordPress/wordpress-develop/blob/7.0/src/wp-admin/network/upgrade.php#L153-L153) * hook[update_wpmu_options](https://developer.wordpress.org/reference/hooks/update_wpmu_options/) * Fires after the network options are updated. * Used by [0 functions](https://developer.wordpress.org/reference/hooks/update_wpmu_options/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/hooks/update_wpmu_options/#uses) | Source: [wp-admin/network/settings.php:132](https://github.com/WordPress/wordpress-develop/blob/7.0/src/wp-admin/network/settings.php#L132-L132) * hook[mu_menu_items](https://developer.wordpress.org/reference/hooks/mu_menu_items/) * Filters available network-wide administration menu options. * Used by [0 functions](https://developer.wordpress.org/reference/hooks/mu_menu_items/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/hooks/mu_menu_items/#uses) | Source: [wp-admin/network/settings.php:503](https://github.com/WordPress/wordpress-develop/blob/7.0/src/wp-admin/network/settings.php#L503-L503) * hook[wpmu_options](https://developer.wordpress.org/reference/hooks/wpmu_options/) * Fires at the end of the Network Settings form, before the submit button. * Used by [0 functions](https://developer.wordpress.org/reference/hooks/wpmu_options/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/hooks/wpmu_options/#uses) | Source: [wp-admin/network/settings.php:535](https://github.com/WordPress/wordpress-develop/blob/7.0/src/wp-admin/network/settings.php#L535-L535) * hook[after_mu_upgrade](https://developer.wordpress.org/reference/hooks/after_mu_upgrade/) * Fires after the Multisite DB upgrade for each site is complete. * Used by [0 functions](https://developer.wordpress.org/reference/hooks/after_mu_upgrade/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/hooks/after_mu_upgrade/#uses) | Source: [wp-admin/network/upgrade.php:114](https://github.com/WordPress/wordpress-develop/blob/7.0/src/wp-admin/network/upgrade.php#L114-L114) * hook[wpmu_upgrade_site](https://developer.wordpress.org/reference/hooks/wpmu_upgrade_site/) * Fires after each site has been upgraded. * Used by [0 functions](https://developer.wordpress.org/reference/hooks/wpmu_upgrade_site/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/hooks/wpmu_upgrade_site/#uses) | Source: [wp-admin/network/upgrade.php:123](https://github.com/WordPress/wordpress-develop/blob/7.0/src/wp-admin/network/upgrade.php#L123-L123) * hook[myblogs_options](https://developer.wordpress.org/reference/hooks/myblogs_options/) * Filters the settings HTML markup in the Global Settings section on the My Sites screen. * Used by [0 functions](https://developer.wordpress.org/reference/hooks/myblogs_options/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/hooks/myblogs_options/#uses) | Source: [wp-admin/my-sites.php:124](https://github.com/WordPress/wordpress-develop/blob/7.0/src/wp-admin/my-sites.php#L124-L124) * hook[myblogs_blog_actions](https://developer.wordpress.org/reference/hooks/myblogs_blog_actions/) * Filters the row links displayed for each site on the My Sites screen. * Used by [0 functions](https://developer.wordpress.org/reference/hooks/myblogs_blog_actions/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/hooks/myblogs_blog_actions/#uses) | Source: [wp-admin/my-sites.php:153](https://github.com/WordPress/wordpress-develop/blob/7.0/src/wp-admin/my-sites.php#L153-L153) * hook[parent_file](https://developer.wordpress.org/reference/hooks/parent_file/) * Filters the parent file of an admin menu sub-menu item. * Used by [0 functions](https://developer.wordpress.org/reference/hooks/parent_file/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/hooks/parent_file/#uses) | Source: [wp-admin/menu-header.php:43](https://github.com/WordPress/wordpress-develop/blob/7.0/src/wp-admin/menu-header.php#L43-L43) * function[do_activate_header()](https://developer.wordpress.org/reference/functions/do_activate_header/) * Adds an action hook specific to this page. * Used by [0 functions](https://developer.wordpress.org/reference/functions/do_activate_header/#used-by) | Uses [1 function](https://developer.wordpress.org/reference/functions/do_activate_header/#uses) | Source: [wp-activate.php:84](https://github.com/WordPress/wordpress-develop/blob/7.0/src/wp-activate.php#L84-L93) * function[wpmu_activate_stylesheet()](https://developer.wordpress.org/reference/functions/wpmu_activate_stylesheet/) * Loads styles specific to this page. * Used by [0 functions](https://developer.wordpress.org/reference/functions/wpmu_activate_stylesheet/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/functions/wpmu_activate_stylesheet/#uses) | Source: [wp-activate.php:101](https://github.com/WordPress/wordpress-develop/blob/7.0/src/wp-activate.php#L101-L113) * function[is_blog_user()](https://developer.wordpress.org/reference/functions/is_blog_user/) * Checks if the current user belong to a given site. * Used by [0 functions](https://developer.wordpress.org/reference/functions/is_blog_user/#used-by) | Uses [3 functions](https://developer.wordpress.org/reference/functions/is_blog_user/#uses) | Source: [wp-includes/deprecated.php:2843](https://github.com/WordPress/wordpress-develop/blob/7.0/src/wp-includes/deprecated.php#L2843-L2847) * hook[allowed_themes](https://developer.wordpress.org/reference/hooks/allowed_themes/) * Filters the array of themes allowed on the network. * Used by [1 function](https://developer.wordpress.org/reference/hooks/allowed_themes/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/hooks/allowed_themes/#uses) | Source: [wp-includes/class-wp-theme.php:1700](https://github.com/WordPress/wordpress-develop/blob/7.0/src/wp-includes/class-wp-theme.php#L1700-L1700) * hook[get_blogs_of_user](https://developer.wordpress.org/reference/hooks/get_blogs_of_user/) * Filters the list of sites a user belongs to. * Used by [1 function](https://developer.wordpress.org/reference/hooks/get_blogs_of_user/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/hooks/get_blogs_of_user/#uses) | Source: [wp-includes/user.php:1148](https://github.com/WordPress/wordpress-develop/blob/7.0/src/wp-includes/user.php#L1148-L1148) * function[get_current_user_id()](https://developer.wordpress.org/reference/functions/get_current_user_id/) * Gets the current user’s ID. * Used by [113 functions](https://developer.wordpress.org/reference/functions/get_current_user_id/#used-by) | Uses [1 function](https://developer.wordpress.org/reference/functions/get_current_user_id/#uses) | Source: [wp-includes/user.php:726](https://github.com/WordPress/wordpress-develop/blob/7.0/src/wp-includes/user.php#L726-L732) * function[get_space_allowed()](https://developer.wordpress.org/reference/functions/get_space_allowed/) * Returns the upload quota for the current blog. * Used by [7 functions](https://developer.wordpress.org/reference/functions/get_space_allowed/#used-by) | Uses [3 functions](https://developer.wordpress.org/reference/functions/get_space_allowed/#uses) | Source: [wp-includes/ms-functions.php:2614](https://github.com/WordPress/wordpress-develop/blob/7.0/src/wp-includes/ms-functions.php#L2614-L2633) * function[welcome_user_msg_filter()](https://developer.wordpress.org/reference/functions/welcome_user_msg_filter/) * Ensures that the welcome message is not empty. Currently unused. * Used by [0 functions](https://developer.wordpress.org/reference/functions/welcome_user_msg_filter/#used-by) | Uses [3 functions](https://developer.wordpress.org/reference/functions/welcome_user_msg_filter/#uses) | Source: [wp-includes/ms-functions.php:2394](https://github.com/WordPress/wordpress-develop/blob/7.0/src/wp-includes/ms-functions.php#L2394-L2416) * function[maybe_add_existing_user_to_blog()](https://developer.wordpress.org/reference/functions/maybe_add_existing_user_to_blog/) * Adds a new user to a blog by visiting /newbloguser/{key}/. * Used by [0 functions](https://developer.wordpress.org/reference/functions/maybe_add_existing_user_to_blog/#used-by) | Uses [8 functions](https://developer.wordpress.org/reference/functions/maybe_add_existing_user_to_blog/#uses) | Source: [wp-includes/ms-functions.php:2222](https://github.com/WordPress/wordpress-develop/blob/7.0/src/wp-includes/ms-functions.php#L2222-L2259) * function[add_existing_user_to_blog()](https://developer.wordpress.org/reference/functions/add_existing_user_to_blog/) * Adds a user to a blog based on details from maybe_add_existing_user_to_blog(). * Used by [1 function](https://developer.wordpress.org/reference/functions/add_existing_user_to_blog/#used-by) | Uses [3 functions](https://developer.wordpress.org/reference/functions/add_existing_user_to_blog/#uses) | Source: [wp-includes/ms-functions.php:2275](https://github.com/WordPress/wordpress-develop/blob/7.0/src/wp-includes/ms-functions.php#L2275-L2293) * hook[added_existing_user](https://developer.wordpress.org/reference/hooks/added_existing_user/) * Fires immediately after an existing user is added to a site. * Used by [1 function](https://developer.wordpress.org/reference/hooks/added_existing_user/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/hooks/added_existing_user/#uses) | Source: [wp-includes/ms-functions.php:2289](https://github.com/WordPress/wordpress-develop/blob/7.0/src/wp-includes/ms-functions.php#L2289-L2289) * function[add_new_user_to_blog()](https://developer.wordpress.org/reference/functions/add_new_user_to_blog/) * Adds a newly created user to the appropriate blog * Used by [0 functions](https://developer.wordpress.org/reference/functions/add_new_user_to_blog/#used-by) | Uses [5 functions](https://developer.wordpress.org/reference/functions/add_new_user_to_blog/#uses) | Source: [wp-includes/ms-functions.php:2309](https://github.com/WordPress/wordpress-develop/blob/7.0/src/wp-includes/ms-functions.php#L2309-L2326) * function[fix_phpmailer_messageid()](https://developer.wordpress.org/reference/functions/fix_phpmailer_messageid/) * Corrects From host on outgoing mail to match the site domain. * Used by [0 functions](https://developer.wordpress.org/reference/functions/fix_phpmailer_messageid/#used-by) | Uses [1 function](https://developer.wordpress.org/reference/functions/fix_phpmailer_messageid/#uses) | Source: [wp-includes/ms-functions.php:2335](https://github.com/WordPress/wordpress-develop/blob/7.0/src/wp-includes/ms-functions.php#L2335-L2337) * function[is_user_spammy()](https://developer.wordpress.org/reference/functions/is_user_spammy/) * Determines whether a user is marked as a spammer, based on user login. * Used by [2 functions](https://developer.wordpress.org/reference/functions/is_user_spammy/#used-by) | Uses [2 functions](https://developer.wordpress.org/reference/functions/is_user_spammy/#uses) | Source: [wp-includes/ms-functions.php:2348](https://github.com/WordPress/wordpress-develop/blob/7.0/src/wp-includes/ms-functions.php#L2348-L2358) [Previous Page](https://developer.wordpress.org/reference/since/mu/?output_format=md) [1](https://developer.wordpress.org/reference/since/mu/?output_format=md) 2 [3](https://developer.wordpress.org/reference/since/mu/page/3/?output_format=md) [4](https://developer.wordpress.org/reference/since/mu/page/4/?output_format=md)… [6](https://developer.wordpress.org/reference/since/mu/page/6/?output_format=md) [Next Page](https://developer.wordpress.org/reference/since/mu/page/3/?output_format=md)