Anuken/Mindustry · error · IOException

Failed to parse server Steam ID: {}

Error message

Failed to parse server Steam ID: {}

What it means

Thrown by connectClient when the 'steamserver:' substring is not a base-10 integer. The value is parsed with Long.parseLong inside a try block; a NumberFormatException is caught and rethrown as this IOException. It is the direct-server analogue of error 120, only differing in which IP prefix triggered it.

Source

Thrown at desktop/src/mindustry/desktop/steam/SNet.java:198

                    currentLobby = null;
                    currentServer = serverID;
                    joinCallback = success;

                    //begin the handshake; success/handleClientReceived/setClientConnected fire once onConnectionStatusChanged reports Connected
                    clientConnection = snet.connectP2P(serverID, 0);

                    Core.app.post(() -> {  // TODO: This gets hidden and I can't figure out how to not do so.
                        ui.loadfrag.show("@connecting");
                        ui.loadfrag.setButton(() -> {
                            ui.loadfrag.hide();
                            netClient.disconnectQuietly();
                        });
                    });

                    Log.info("Initiated direct Steam P2P connection to server: @", currentServer.getAccountID());
                });
            }catch(NumberFormatException e){
                throw new IOException("Failed to parse server Steam ID: " + server);
            }
        }else{
            provider.connectClient(ip, port, success);
        }
    }

    @Override
    public void sendClient(Object object, boolean reliable){
        if(isSteamClient()){
            if(currentServer == null || clientConnection == null){
                Log.info("Not connected, quitting.");
                return;
            }

            try{
                clientWriteBuffer.limit(clientWriteBuffer.capacity());
                clientWriteBuffer.position(0);
                serializer.write(clientWriteBuffer, object);

View on GitHub (pinned to f695ad7e60)

Solutions

1. Trim and validate the 'steamserver:' substring as digits-only (regex ^\d+$) before connectClient.
2. Reject a hex-prefixed value explicitly, since '0x...' is numeric-looking but not base-10.
3. Normalize the connect string at the UI boundary so trailing whitespace/newlines never reach connectClient.
4. Share one validation helper with the 'steam:' path (error 120) to keep both prefixes consistent.

Example fix

// before
String server = ip.substring("steamserver:".length());
SteamID serverID = SteamID.createFromNativeHandle(Long.parseLong(server));

// after
String server = ip.substring("steamserver:".length()).trim();
if(!server.matches("\\d+")) throw new IOException("Failed to parse server Steam ID (not numeric): " + server);
SteamID serverID = SteamID.createFromNativeHandle(Long.parseLong(server));

// Run before connectClient when ip starts with "steamserver:"
String server = ip.substring("steamserver:".length()).trim();
if(server.isEmpty() || !server.matches("\\d+")){
    throw new IllegalArgumentException("Steam server ID must be numeric: '" + server + "'");
}

static OptionalLong parseSteamServerHandle(String ip){
    if(ip == null || !ip.startsWith("steamserver:")) return OptionalLong.empty();
    String s = ip.substring("steamserver:".length()).trim();
    return s.matches("\\d+") ? OptionalLong.of(Long.parseLong(s)) : OptionalLong.empty();
}

try{
    net.connectClient(ip, port, success);
}catch(IOException e){
    if(e.getMessage() != null && e.getMessage().startsWith("Failed to parse server Steam ID")){
        ui.showErrorMessage("@invalidsteam.server");
    }else throw e;
}

When it happens

Trigger: Calling connectClient("steamserver:<value>", ...) where <value> is empty or contains non-digit characters (e.g. 'steamserver:abc', 'steamserver:', 'steamserver:0x1A').

Common situations: User pastes a server connect string with extra decoration; launcher feeds an untrimmed or hex-formatted value; a copy-paste drops part of the ID; an automated script passes the wrong field.

Understand the failure class

• Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

Related errors

• Invalid Steam ID structure: {}
• Invalid Steam ID: {}
• Player cannot configure a tile.
• Player cannot control a building.
• Player cannot control a unit.

AI-assisted analysis of Anuken/Mindustry@f695ad7e60 (2026-08-14). Data as JSON: /api/errors/af2e8087ee7a7c1a. Report an issue: GitHub.