Browser connection errors
"This site can't be reached" is not a diagnosis — the small code underneath it is. Each of these errors points at a different failure, and each has a different fix.
Chrome, Edge, Brave
ERR_CONNECTION_REFUSED
The server was reached and actively refused the connection. The machine is online; nothing is listening on the port you asked for.…
Chrome, Edge
DNS_PROBE_FINISHED_NXDOMAIN
DNS returned "no such domain". The name could not be turned into an IP address at all, so no connection was ever attempted.…
Chrome, Edge
ERR_NAME_NOT_RESOLVED
The browser could not resolve the hostname. Effectively the same condition as NXDOMAIN, reported by a different part of Chrome.…
Chrome, Edge
ERR_CONNECTION_TIMED_OUT
The browser sent packets and nothing came back within the time limit. Unlike a refused connection, this is silence rather than rej…
Chrome, Edge
ERR_SSL_PROTOCOL_ERROR
The TLS handshake failed before any page could load. The server answered, but the two sides could not agree on a secure connection…
Chrome, Edge
NET::ERR_CERT_AUTHORITY_INVALID
The certificate was not issued by an authority the browser trusts — commonly a self-signed certificate, or a missing intermediate.…
Chrome, Edge
NET::ERR_CERT_DATE_INVALID
The certificate is outside its validity window — nearly always expired, occasionally not yet valid.…
Chrome, Edge
NET::ERR_CERT_COMMON_NAME_INVALID
The certificate is valid but does not cover the hostname in the address bar.…
Chrome, Edge
ERR_TOO_MANY_REDIRECTS
The browser followed redirect after redirect until it gave up. Two rules are almost certainly pointing at each other.…
Chrome, Edge
ERR_EMPTY_RESPONSE
The connection opened, then the server closed it without sending anything at all.…
Chrome, Edge
ERR_CONNECTION_RESET
The connection was closed abruptly mid-conversation by a TCP reset.…
all browsers
503 Service Unavailable
The server is reachable and answering, but is temporarily unable to serve the request — overloaded, or in maintenance mode.…
all browsers
502 Bad Gateway
A proxy or load balancer could not get a valid response from the application behind it.…
Chrome, Edge
This site can't be reached
Chrome's generic wrapper around several distinct faults. The specific cause is the code printed underneath in small text — that is…