Guides from the NOC

Chrome prints the same headline for a dozen unrelated failures. The capitalised code underneath is the real error - here is what each one means.

The DNS server your device is pointed at is not answering. This is a configuration problem on your side, and the fix is almost always one setting.

Chrome could not reach any DNS server at all. That usually means the connection is down - but not always, and the exception is worth knowing.

An HTTP/2 stream was rejected as malformed. Usually a bad header, a proxy that mangles frames, or PHP emitting output after the response - here is how to find which.

Chrome tried to write a request to a socket that was no longer connected. This one is nearly always local - here is the order to check things in.

HTTP/3 runs over UDP, and plenty of networks handle UDP badly. Here is how to confirm QUIC is the cause in thirty seconds, and what to fix rather than just disabling it.

Chrome aborts a request when the network changes mid-flight. Usually harmless, sometimes a symptom - here is how to tell which, and how to stop it happening.

The connection opened, the request went out, and the server closed it without sending a response. Here is how to find out which layer hung up, and why.

The lookup failed before anything was dialled. Here is how to tell a missing DNS record from a resolver problem on your own machine, and fix whichever one it is.

Chrome says the address is unreachable when the network cannot get a packet to that IP at all. Here is how to tell a stale DNS record from a routing problem.

Getting DNS_PROBE_FINISHED_NXDOMAIN in Chrome? Here's how to tell if it's your device, your DNS records, or nameserver propagation - and how to fix each.

Site flagged as 'Dangerous' or 'Deceptive' in Chrome? Learn how to check Safe Browsing status, request a Google review, and get delisted fast.

Getting ERR_SSL_PROTOCOL_ERROR in Chrome? Learn why the browser can't even start a TLS handshake and how to fix it on cPanel, Nginx, Apache, or Cloudflare.

Getting ERR_SSL_VERSION_OR_CIPHER_MISMATCH in Chrome? Learn why it's a TLS handshake failure, not a bad cert, and fix it on cPanel, Nginx, or Cloudflare.

Chrome shows 'Not Secure' after cPanel AutoSSL renews? Learn the real causes-CAA records, Cloudflare, mixed content-and fix them step by step.