Chrome, when the proxy refuses the CONNECT tunnel.
ERR_TUNNEL_CONNECTION_FAILED
Chrome asked the proxy to open a tunnel for HTTPS and the proxy did not. It is Chrome's way of surfacing what is usually a 407 or a refused connection underneath.
A proxy does not fix this. This never reaches a target site. It is a connection problem between your browser and the proxy, so it is configuration rather than blocking.
Why it happens
Credentials required but Chrome could not supply them — the --proxy-server flag cannot carry a password.
The proxy host or port is wrong, or the port does not accept CONNECT.
The machine is not on the IP whitelist.
A local firewall blocking the outbound proxy port.
How to fix it
- Test the same host and port with curl -x. If curl works and Chrome does not, it is the credential path.
- For authenticated proxies in Chrome, whitelist the IP or use an extension that answers the auth challenge.
- Check you are using an HTTP port for HTTP proxying and a SOCKS port for SOCKS.
Test the proxy from hereRuns from our server, so a local firewall cannot skew the answer.
FAQ
What does ERR_TUNNEL_CONNECTION_FAILED mean?›
Chrome asked the proxy to open a tunnel for HTTPS and the proxy did not. It is Chrome's way of surfacing what is usually a 407 or a refused connection underneath. Chrome, when the proxy refuses the CONNECT tunnel.
Why am I getting ERR_TUNNEL_CONNECTION_FAILED?›
Credentials required but Chrome could not supply them — the --proxy-server flag cannot carry a password. The proxy host or port is wrong, or the port does not accept CONNECT. The machine is not on the IP whitelist. A local firewall blocking the outbound proxy port.
How do I fix ERR_TUNNEL_CONNECTION_FAILED?›
Test the same host and port with curl -x. If curl works and Chrome does not, it is the credential path. For authenticated proxies in Chrome, whitelist the IP or use an extension that answers the auth challenge. Check you are using an HTTP port for HTTP proxying and a SOCKS port for SOCKS.
Will a proxy fix ERR_TUNNEL_CONNECTION_FAILED?›
This never reaches a target site. It is a connection problem between your browser and the proxy, so it is configuration rather than blocking.