421 Misdirected Request on DirectAdmin

Issue

After upgrading Apache to version 2.4.65, all hosted sites began returning the error 421 Misdirected Request.

Environment

• CloudLinux
• DirectAdmin
• Apache

Solution

The latest Apache release introduced stricter SSL/TLS handling to address security vulnerabilities, which causes incompatibility with proxies that do not send SNI in their upstream connections. The 421 error occurs when the server cannot match the request to a virtual host because of missing SNI data.

1. To resolve the issue, add these config lines to your nginx config:

proxy_ssl_name $host;                       
proxy_ssl_server_name on;      

2. After adding the lines in the config, run build rewrite_confs

cd /usr/local/directadmin/custombuild
./build rewrite_confs             

Cause

Apache 2.4.64 introduced stricter SSL/TLS handling (to address CVEs), which leads to incompatibility with proxies that don’t include SNI in their upstream connections.

Useful links

https://kb.bangmod.cloud/article/directadmin-website-error-421-misdirected-request 

https://forum.directadmin.com/threads/all-sites-with-error-412-misdirected-request-directadmin-and-cloudlinux.74291/ 

https://cloudlinux.zendesk.com/hc/en-us/articles/21282870470172-421-Misdirected-Request-Error-After-Recent-ea-apache-Update