commaai/openpilot · error

error: unexpected argument %s

Error message

error: unexpected argument %s

What it means

Printed by cabana's parseArgs for a non-option positional argument when the route has already been set — cabana accepts exactly one positional (the route). The second bare argument fails on the `a[0] == '-'` chain's final else; usage is printed and the process exits 1.

Source

Thrown at openpilot/tools/cabana/cabana.cc:119

      fprintf(stderr, "error: --socketcan is only supported on Linux\n");
      return 1;
#endif
    } else if (std::strcmp(a, "--zmq") == 0) {
      if (!takeValue(argc, argv, i, args.zmq)) return 1;
    } else if (std::strcmp(a, "--data_dir") == 0) {
      if (!takeValue(argc, argv, i, args.data_dir)) return 1;
    } else if (std::strcmp(a, "--no-vipc") == 0) {
      args.no_vipc = true;
    } else if (std::strcmp(a, "--dbc") == 0) {
      if (!takeValue(argc, argv, i, args.dbc)) return 1;
    } else if (a[0] == '-') {
      fprintf(stderr, "error: unknown option %s\n", a);
      printUsage(argv[0]);
      return 1;
    } else if (args.route.empty()) {
      args.route = a;
    } else {
      fprintf(stderr, "error: unexpected argument %s\n", a);
      printUsage(argv[0]);
      return 1;
    }
  }
  ok = true;
  return 0;
}

}  // namespace

int main(int argc, char *argv[]) {
  QCoreApplication::setApplicationName("Cabana");
  initApp(argc, argv, false);
  QApplication app(argc, argv);
  app.setApplicationDisplayName("Cabana");
  //app.setWindowIcon(QIcon(":cabana-icon.png"));  // TODO: do this in imgui

  UnixSignalHandler signalHandler;

View on GitHub (pinned to 516ec1e682)

Solutions

1. Quote the route: cabana "abcdef--/2" so it stays one argument.
2. Pass only one route per invocation; run cabana again for the next route.
3. Remove stray trailing arguments (accidentally pasted text, empty-but-split variables).

Example fix

# before
cabana my route --/2        # 'route --/2' -> unexpected argument

# after
cabana "my route --/2"

positionals = [a for a in sys.argv[1:] if not a.startswith('-')]
if len(positionals) > 1:
    raise SystemExit('cabana takes exactly one route argument')
subprocess.run(['cabana', *sys.argv[1:]])

When it happens

Trigger: Running `cabana ROUTE1 ROUTE2`, or an unquoted route string with spaces splitting into two argv entries (e.g. 'a b--/2'), or a trailing stray word after the route.

Common situations: Unquoted route names containing spaces or special shell characters, shell glob expansion producing multiple tokens, or attempts to open multiple routes at once which cabana does not support.

Related errors

• error: %s requires a value
• error: unknown option %s
• usage: encoderd --clip OUTPUT START DURATION [--bitrate BPS]
• clip encoding failed: %s
• error: --socketcan is only supported on Linux

AI-assisted analysis of commaai/openpilot@516ec1e682 (2026-08-15). Data as JSON: /api/errors/1ac2b2159254c080. Report an issue: GitHub.