ERR_QUIC_PROTOCOL_ERROR
The HTTP/3 (QUIC) connection failed
Seen in Chrome, Edge
The browser tried HTTP/3 over QUIC (UDP) and the connection broke in a way it couldn't recover from.
Common causes
- A firewall, proxy or security software interferes with UDP 443 traffic.
- A server or CDN advertises HTTP/3 (Alt-Svc header) but its QUIC setup is broken.
- A VPN or network with a small MTU drops QUIC packets.
How to fix it
- As a test, disable QUIC at chrome://flags/#enable-quic; if that fixes it, the network or server QUIC path is at fault.
- On managed devices, the QuicAllowed policy can turn QUIC off while the cause is fixed.
- Server side, check the HTTP/3 configuration or stop advertising it in Alt-Svc until it works.
Got a different message? Paste it into the error explainer.
Related errors
- ERR_TOO_MANY_REDIRECTS · The page redirects in a loop
- ERR_CONNECTION_CLOSED · The server closed the connection unexpectedly
- ERR_EMPTY_RESPONSE · The server didn't send any data
- ERR_HTTP2_PROTOCOL_ERROR · The HTTP/2 response was malformed or cut short
- NET::ERR_CERT_DATE_INVALID · The certificate has expired or is not yet valid
- NET::ERR_CERT_AUTHORITY_INVALID · The certificate isn't issued by a trusted authority
- SEC_ERROR_UNKNOWN_ISSUER · Firefox doesn't recognise the certificate's issuer
- NET::ERR_CERT_COMMON_NAME_INVALID · The certificate doesn't cover this name
- ERR_SSL_PROTOCOL_ERROR · The secure connection failed during the handshake
- ERR_SSL_VERSION_OR_CIPHER_MISMATCH · No TLS version or cipher in common
- You cannot visit this site right now because the website uses HSTS · HSTS blocks the bypass of a certificate error
- NET::ERR_CERT_REVOKED · The certificate has been revoked by its issuer