Overview
Following a recent update to Apache, websites hosted on Plesk with Ubuntu may become inaccessible, displaying the error:
421 Misdirected Request
Symptoms
Cause
The latest Apache release includes security fixes for CVEs affecting Apache and nginx interoperability. These changes prevent Apache from processing requests from nginx that lack a server name. By default, nginx does not pass the server name via SNI (Server Name Indication) when connecting to a proxied HTTPS server.
The Plesk team is currently preparing a custom fix for Plesk Obsidian versions 18.0.70 and 18.0.71. You can click “Follow” on the relevant Knowledge Base article to receive updates.
Resolution
To resolve the issue, update the nginx configuration to ensure the server name is passed to Apache via the TLS SNI extension.
Steps:
- Connect to your Plesk server using SSH.
- Run the following script without making any changes:
echo -e "proxy_ssl_server_name on;\nproxy_ssl_name \$host;" >
/etc/nginx/conf.d/fixssl.conf && service nginx restart
This will enable nginx to correctly forward the server name, restoring access to your hosted websites.
