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.
Read more: Why Your Website Might Be Throwing a 421 SNI Error (And What to Do About It)
Story added 30. July 2025, content source with full text you can find at link above.