Elementor: 404 Not Found on document save

When you click Update in Elementor the editor sends a POST request to admin-ajax.php or the Elementor REST endpoint. The server returns a 404 response. WordPress interprets the response as a missing page and redirects the editor to a 404 screen. No changes are stored.

The 404 originates from the request never reaching the proper handler. A Web Application Firewall such as ModSecurity may block the POST payload. Custom rewrite rules in .htaccess can also capture the URL and serve a generic 404 page. An invalid nonce or a disabled REST API produces the same result because WordPress rejects the request before processing.

Large pages increase the request size. When the payload exceeds server limits the request aborts and the server returns a 404 instead of a detailed error. A CDN or page‑cache layer may serve a stale 404 for the endpoint, making the problem appear intermittent.