Help CenterConnection IssuesError codes explained
Connection Issues

Error codes explained

4 min read·Updated May 10, 2026

What each HorizonVPN error code means and how to resolve it.

  • ERR_CONNECTION_TIMEOUT — Server took too long to respond. Try a different server or protocol.
  • ERR_AUTH_FAILED — Invalid credentials or expired session. Log out and sign in again.
  • ERR_TUN_FAILED — Failed to create virtual network adapter. Reinstall the TAP driver (Windows) or restart the app.
  • ERR_DNS_FAILED — DNS resolution failed through the VPN. Check DNS settings or try another server.
  • ERR_FIREWALL_BLOCKED — Local firewall blocking the VPN. Add HorizonVPN as a firewall exception.
  • ERR_PROTOCOL_UNSUPPORTED — Network is blocking the selected protocol. Switch to OpenVPN TCP.
  • ERR_SERVER_FULL — Server at capacity. Connect to a different server in the same region.
  • ERR_ACCOUNT_EXPIRED — Subscription ended. Log in to your account to renew.

Copy the full error message and paste it in live chat — our support team can identify the issue immediately.

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