A WordPress security check failed.
WHAT IT MEANS
A nonce, the token WordPress uses to verify that a request came from where it claims, was missing or expired.
THE COMMON CAUSES
The page sat open too long before submitting, and the token expired A caching plugin cached a page containing a token A plugin conflict Session or cookie problems
THE SIMPLE FIX
Reload the page and try again. An expired token resolves itself.
IF IT PERSISTS
Clear all caches, including any caching plugin and Cloudflare.
Admin pages should never be cached. Check your caching plugin excludes the admin area.
DURING UPLOADS
Frequently a file size limit rather than a genuine security problem. Raise upload_max_filesize and post_max_size in cPanel.
WordPress sometimes reports this misleadingly when a POST request exceeds limits.
IF IT HAPPENS ON EVERY ADMIN ACTION
A cookie problem. Check that the site URL matches the address you are visiting, particularly www versus non-www.
A mismatch prevents cookies being read and produces this consistently.
