🎮 Game Error Codes What it means & how to fix it

Icarus Won't Connect to a Dedicated Server? Here's the Fix

When Icarus won't connect to a dedicated server — it's not in the list, throws 'failed to connect', or drops during load — it's usually a port-forwarding gap, a server config error, or a build mismatch. Fastest fix in 2026: forward UDP 17777/27015, confirm the server finished starting, and match the server and client versions.

Icarus dedicated server — exact ports, config & connect fix

Game port (UDP)
17777
Query port (UDP)
27015
Launch params
-Port=17777 -QueryPort=27015
Server config file
Icarus\Saved\Config\WindowsServer\ServerSettings.ini
Common cause of 'cannot connect'
ServerSettings.ini only appears AFTER first launch; both 17777 and 27015 must be forwarded as UDP (not TCP)

Last verified: September 2026

Error codes

Server not appearing in list Your dedicated server isn't visible to clients

Cause: Query ports aren't forwarded or the server hasn't fully registered.

Fix:
  1. Forward UDP ports 17777 (game) and 27015 (query) on the router.
  2. Wait until the console confirms the server registered before searching.
  3. Check the server's ServerSettings for a correct name and network config.
  4. Use Direct Connect (Join IP) with the host's public IP and game port.
Failed to connect / timeout The client can't complete the handshake

Cause: Firewall blocking, strict NAT, or wrong IP/port.

Fix:
  1. Allow Icarus and the dedicated server through Windows Firewall.
  2. Set router NAT to Open or enable UPnP for the forwarded ports.
  3. Double-check you're using the host's current public IP.
  4. Restart the router to refresh the NAT mapping, then retry.
Version mismatch / kicked on load Client and server are on different Icarus builds

Cause: The server or client updated separately.

Fix:
  1. Update the dedicated server via SteamCMD to the latest build.
  2. Update Icarus on the client so builds match.
  3. Opt out of any beta/experimental branch on both sides.
  4. Restart the server after updating so it re-registers cleanly.

Fixes that work for most Icarus errors

  1. Forward UDP 17777 (game) and 27015 (query) on the host router.
  2. Wait for the server console to confirm registration before joining.
  3. Allow Icarus and the server executable through Windows Firewall.
  4. Set NAT to Open or enable UPnP; verify the correct public IP.
  5. Match server and client builds; update both after any patch.
  6. Use Direct Connect (Join IP) if the server still won't list.

FAQ

What ports does an Icarus dedicated server need?

UDP 17777 for the game and 27015 for the Steam query. Forward both on your router (or enable UPnP) so the server lists and clients can connect.

Why isn't my Icarus dedicated server showing up?

Usually the query port (27015) isn't forwarded or the server hasn't finished registering. Forward the ports, wait for the console to confirm registration, or use Direct Connect with the public IP.

How do I fix an Icarus version mismatch?

Update the dedicated server via SteamCMD and update the client so both are on the same build, opt out of experimental branches, then restart the server.

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