Some customers experienced an issue where websites hosted on our Linux Plesk servers displayed a "421 Misdirected Request" error. This occurred after a recent Apache update introduced changes that affected compatibility with Nginx. The issue has since been identified and resolved.
Details:
Following the Apache update, websites using Nginx as a reverse proxy in front of Apache, common in Plesk environments, began showing the 421 error. The update included security improvements that changed how Apache handles HTTPS requests. Specifically, Apache now requires the server name to be sent using SNI (Server Name Indication) during the SSL handshake. By default, Nginx does not include this server name when proxying HTTPS traffic, which caused Apache to reject the connection.
Our team implemented a fix by updating the Nginx configuration to properly pass the server name via SNI. This allows Apache to handle requests as expected and restores access to affected websites. No action is needed on your part; all changes have been made server-side.
This issue is now resolved, and all Plesk-hosted websites should be operating normally.