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MCPX_HTTP_DNS_FAILED

Severity: error Domain: HTTP

What happened​

mcpproxy could not resolve the hostname in the upstream server URL. The underlying error is from the OS resolver (getaddrinfo).

Common causes​

  • Typo in the hostname.
  • VPN / corporate split-DNS not connected.
  • The hostname only resolves inside a private network and the host is offline from that network.
  • DNS over HTTPS / DoH proxy is misconfigured.
  • /etc/hosts overrides interfering.

How to fix​

# Verify the hostname:
dig <hostname>            # should print A/AAAA records
host <hostname>
nslookup <hostname>

If dig works but mcpproxy doesn't, the difference is usually:

  • A VPN that's only active in the launching shell.
  • A HOSTALIASES or /etc/hosts override visible in the shell but not the GUI.

VPN / split DNS​

Make sure your VPN client is started before mcpproxy if the MCP server lives inside the corporate network. Tray apps inherit the GUI environment, not the shell environment.

Override hostname in config​

If the hostname is unstable but the IP is known:

{ "url": "https://203.0.113.10/mcp", "tls_server_name": "internal.example.com" }

Use tls_server_name to keep TLS verification working.