bazelbuild/bazel · error · OptionsParsingException

Not a valid : ' ' (should be auto or a boolean)

Error message

Not a valid %s: '%s' (should be auto or a boolean)

What it means

Thrown by the TriState converter (Converters line 174) when the input is neither "auto" nor one of the accepted boolean spellings (true/1/yes/t/y, false/0/no/f/n, case-insensitive). TriState options distinguish "explicitly on", "explicitly off", and "not set / automatic", so arbitrary strings are rejected at parse time.

Solutions

1. Use auto to let the flag decide automatically, or one of the boolean spellings (e.g. yes/no) for an explicit choice.
2. To unset a TriState flag, simply omit it from the command line or use auto.
3. Update stale scripts that still write on/off.

Example fix

# before
bazel build --my_tristate=on //...
# after
bazel build --my_tristate=yes //...

boolean isParsableTriState(String s) {
  if (s == null) return false;
  String v = s.toLowerCase(Locale.ROOT);
  return v.equals("auto")
      || Set.of("true","1","yes","t","y","false","0","no","f","n").contains(v);
}

boolean isTriStateFlagValue(String s) {
  return s != null && s.matches("(?i)(auto|true|false|1|0|yes|no|t|f|y|n)");
}

When it happens

Trigger: Passing --my_tristate=maybe, --my_tristate=unset, or --my_tristate="" to a TriState-typed option; also passing on/off which this converter does not accept.

Common situations: Users assuming on/off works because other tools accept it; trying to "reset" a flag by giving an empty value instead of auto; script defaults that fall back to an invalid token.

Related errors

• Empty values are not allowed as part of this " +…
• Illegal duration '" + input + "'.
• '" + input + "' is not a boolean
• '" + input + "' is not a double
• '" + input + "' is not a long

AI-assisted analysis of bazelbuild/bazel@e6e199d060 (2026-08-14). Data as JSON: /api/errors/69eb8103ff7fbb52. Report an issue: GitHub.

Appendix: source

Thrown at src/main/java/com/google/devtools/common/options/Converters.java:174

      super(TriState.class, "tri-state (auto, yes, no) option value");
    }

    @Override
    public TriState convert(@Nullable String input) throws OptionsParsingException {
      if (input == null) {
        return TriState.AUTO;
      }
      input = Ascii.toLowerCase(input);
      if (input.equals("auto")) {
        return TriState.AUTO;
      }
      if (ENABLED_REPS.contains(input)) {
        return TriState.YES;
      }
      if (DISABLED_REPS.contains(input)) {
        return TriState.NO;
      }
      throw new OptionsParsingException(
          "Not a valid %s: '%s' (should be auto or a boolean)".formatted(typeName, input));
    }

    @Override
    public String getTypeDescription() {
      return "a tri-state (auto, yes, no)";
    }
  }

  /**
   * Standard "converter" for Void. Should not actually be invoked. For instance, expansion flags
   * are usually Void-typed and do not invoke the converter.
   */
  public static class VoidConverter extends Converter.Contextless<Void> {
    @Override
    public Void convert(String input) throws OptionsParsingException {
      if (input == null || input.equals("null")) {
        return null; // expected input, return is unused so null is fine.

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