Fix ERR_
Diagnose Chrome ERR_PROXY_CONNECTION_FAILED by checking the proxy endpoint, system settings and client behavior without disabling security protections.
ERR_PROXY_CONNECTION_FAILED means Chrome could not establish a connection to the configured proxy. Start with the proxy address and active browser settings. Chromium defines a separate error for a failed tunnel through a proxy, so preserve the exact error message.
Read the exact Chrome error
Chromium distinguishes failure to connect to a proxy from failure to open a tunnel through it. Record the complete error code. ERR_PROXY_CONNECTION_FAILED directs you to the proxy endpoint and connection path; ERR_TUNNEL_CONNECTION_FAILED needs a separate check of the tunnel response.
Record the error before changing anything. Check whether the same browser fails on every small HTTPS page or only on the destination you were using. If the page returns an HTTP status instead, follow that response rather than treating it as a connection failure.
References: Chromium network errors
Check the issued host, port and protocol
- Compare the proxy endpoint with the active rental details. Do not enter the dashboard URL as the proxy host.
- Use the issued HTTP or SOCKS5 port for the selected protocol. The destination being HTTPS does not mean that the proxy itself accepts a TLS connection.
- Check for a copied space, a stale port or credentials from a different rental. Keep the original settings so you can restore them.
- Confirm that the rental is still active before repeating connection attempts.
References: Chromium proxy protocols and authentication
Identify which setting controls Chrome
Chrome can take proxy settings from the operating system, policy, a configuration script or browser configuration. A proxy extension may also control the browser. Check the active source before editing another setting that has no effect.
If you use a managed computer, ask its administrator which proxy configuration applies. For a test profile you own, compare it with a clean profile using the same intended proxy. Record any difference in extensions or configuration. Do not delete your main profile to run this comparison.
Keep the firewall and certificate verification enabled. If the network denies the connection, give the administrator the intended endpoint and observed error. Disabling protection obscures the cause and changes more than the proxy configuration.
References: Chromium proxy protocols and authentication
Compare the browser with a second client
Use curl with the same issued endpoint and a small HTTPS URL. Keep the credentials in a private configuration file instead of a copied command or screenshot. The authentication guide below includes the file format.
If curl also cannot connect, check the endpoint and rental state, then compare from another permitted network. If curl succeeds, compare the protocol and authentication method Chrome is using. Native Chrome SOCKS5 does not support proxy authentication, even when another SOCKS5 client accepts the same credentials.
- Set up a private curl authentication check
- Compare differences between clients
- Check Chrome SOCKS5 authentication support
References: Chromium proxy protocols and authentication; curl proxy and configuration options
Compare an unreachable proxy with a rejected tunnel
In our 13 November 2026 loopback test, curl 8.7.1 returned exit 7 and CONNECT 000 for a closed proxy port. A reachable fixture returning CONNECT 502 produced exit 56. Neither test contacted a destination. These are curl observations, so they help interpret the second-client check rather than predict the Chrome message.
Act on the result
If the endpoint was wrong, correct that field and repeat the original request. If the endpoint is correct but unreachable from your client, send support the time, protocol, error and result of the second-client check. Include the rental ID through the support portal, without its password.
If the error changes to 407, continue with authentication checks. If the request starts working but has the wrong country, record the exit IP in that browser and compare it with the rental details.