ERR_TUNNEL_CONNECTION_FAILED, what it means and how to fix it

For HTTPS sites, Chrome asks the proxy to open a tunnel (an HTTP CONNECT) to the destination. This error means the proxy was reached but the tunnel was not: the proxy refused the request, demanded sign-in that failed, or could not reach the site itself. The fault sits with the proxy or its rules far more often than with the website.

The fix, in order

  1. Reload once. Proxy tunnels fail transiently under load; a single retry separates a hiccup from a policy.
  2. Complete the proxy sign-in if one is pending. On work and school networks, open any plain HTTP page or the network's sign-in page and authenticate; unauthenticated tunnels are refused by design.
  3. Check whether the site is on the proxy's block list. If only certain categories of site fail (webmail, social, streaming) while work sites load, the proxy is filtering, and the failure is policy, not breakage.
  4. Reconnect your VPN if the proxy lives behind it. A half-connected VPN leaves the proxy reachable enough to answer but unable to route onward.
  5. Home users who set no proxy: check for a leftover one. Settings → Network & internet → Proxy. Removing a dead manual proxy removes this error with it.

If it still happens

If the tunnel fails for one specific site through a required work or school proxy, the proxy administrator is the only one who can see why; give them the site, the time, and the exact error text. There is no visitor-side setting that overrides a proxy's refusal.

Common questions

What is a proxy tunnel? For an HTTPS site, the proxy cannot see inside the encrypted traffic, so the browser asks it to open a raw tunnel to the site and passes encrypted data through it. The CONNECT request that opens the tunnel is what failed here.

Can the website itself cause ERR_TUNNEL_CONNECTION_FAILED? Almost never directly. The website never sees the request; the failure happens between the browser and the proxy or between the proxy and the site, and the proxy's own reachability or rules decide it.

Related errors

ERR_PROXY_CONNECTION_FAILED · ERR_SSL_PROTOCOL_ERROR · ERR_CONNECTION_FAILED