WordPress multisite user permissions are much more restrictive than on WordPress single site. One such change is that on multisite only super-admin users have the ‘unfiltered_html’ capability. It is possible however to restore our desired user permissions on multisite using a filter on the 'map_meta_cap'hook.
map_meta_cap
The map_meta_cap hook can be used to provide additional capabilities to users who would otherwise not have them. There is further documentation on WordPress user roles and capabilities here: https://wordpress.org/documentation/article/roles-and-capabilities/.
Let’s say we would like for any user who can edit posts to also have the ability to use ‘unfiltered_html’ (not necessarily recommended, just the example used here). We can do this by adding a filter to 'map_meta_cap':
/**
* Enable unfiltered_html capability for some users
*
* @param array $caps user's capabilities
* @param string $cap capability type
* @param int $user_id the user ID
* @return array $caps The modified user capabilities
*/
function nwd_unfiltered_html_capability( $caps, $cap, $user_id ) {
if ( 'unfiltered_html' === $cap && user_can( $user_id, 'edit_posts' ) ) {
$caps = array( 'unfiltered_html' );
}
return $caps;
}
add_filter( 'map_meta_cap', 'nwd_unfiltered_html_capability', 1, 3 );Additional Resources
If WordPress filters seem mysterious (as they once did to me), have a look at this article https://neilsonwebdesign.com/wordpress-add-filter-and-apply-filters/, which explains filters in more detail.
