NationalSecurityAgency/ghidra · error · IllegalArgumentException

Unexpected argument: {}

Error message

Unexpected argument: {}

What it means

Thrown when, after shortcut resolution, the resolved `option` token does not start with '--'. This catches bare positional values or stray tokens that appear in the options portion of the command line where an option flag is expected.

Source

Thrown at Ghidra/Features/BSim/src/main/java/ghidra/features/bsim/query/BSimControlLaunchable.java:276

				// although not prefered, allow option value to be specified as --option=value
				int ix = optionName.indexOf("=");
				if (ix > 1) {
					value = optionName.substring(ix + 1);
					optionName = optionName.substring(0, ix);
				}
			}

			String option = optionName;

			if (optionName.startsWith("-") && !optionName.startsWith("--")) {
				option = SHORTCUT_OPTION_MAP.get(optionName); // map option to -- long form
				if (option == null) {
					throw new IllegalArgumentException("Unsupported option use: " + optionName);
				}
			}

			if (!option.startsWith("--")) {
				throw new IllegalArgumentException("Unexpected argument: " + option);
			}

			if (!GLOBAL_OPTIONS.contains(option) && !allowedParams.contains(option)) {
				throw new IllegalArgumentException("Unsupported option use: " + optionName);
			}

			if (!VALUE_OPTIONS.contains(option)) {
				// option without value arg
				if (value != null) {
					throw new IllegalArgumentException(
						"Unsupported option specification: " + optionName + "=");
				}
			}
			else if (StringUtils.isBlank(value)) {
				// consume next param as option value
				if (++i == params.length) {
					throw new IllegalArgumentException("Missing option value: " + optionName);
				}

View on GitHub (pinned to d5f144c24d)

Solutions

1. Prefix the value with its intended option flag, e.g. `--port 5432`.
2. Re-check argument ordering: required positional parameters come first, then options.
3. Confirm no stray tokens leaked in from shell expansion.

Example fix

// before
bsim control configure myhost 5432
// after
bsim control configure myhost --port 5432

// Reject bare tokens that look like values, not options, in the options region.
for (String t : optionTokens) {
    if (!t.startsWith("-")) {
        System.err.println("Unexpected non-option argument: " + t + ". Did you omit a --flag?");
        return;
    }
}

try {
    launchable.readOptions(command, params, discard);
} catch (IllegalArgumentException e) {
    if (e.getMessage().startsWith("Unexpected argument:")) {
        System.err.println("An option flag may be missing before: " + e.getMessage());
    }
    throw e;
}

When it happens

Trigger: A token that does not start with '-' at all (a raw value) reaches the option loop, so `option` stays as the bare token and fails the `option.startsWith("--")` check at line 276.

Common situations: Forgetting the option flag before a value (e.g. a port number with no `--port`), placing positional arguments in the wrong slot, or a value whose preceding flag was dropped.

Related errors

• Unknown command: {}
• Unsupported command: {}
• Unsupported option use: {}
• Unsupported option specification: {}=
• Missing option value: {}

AI-assisted analysis of NationalSecurityAgency/ghidra@d5f144c24d (2026-08-14). Data as JSON: /api/errors/67eab435f5ba854d. Report an issue: GitHub.