Why Your Website Might Be Throwing a 421 SNI Error (And What to Do About It)

So, your support team is suddenly flooded with tickets about “421 Misdirected Request” errors, and you’re wondering if the internet is just having a bad day. Spoiler: it’s not. But Apache might be.

Let’s break down what’s going on, why it’s happening now, and how to fix it—whether you’re using Plesk, cPanel, or flying solo with your own Apache setup.

What Is a 421 SNI Error Anyway?

The HTTP 421 “Misdirected Request” error is Apache’s way of saying:

“Hey, I wasn’t expecting you on this connection.”

This happens when the Server Name Indication (SNI) in the TLS handshake doesn’t match the hostname Apache is expecting.

Continue reading Why Your Website Might Be Throwing a 421 SNI Error (And What to Do About It) at Sucuri Blog.