bazelbuild/bazel · error · OptionsParsingException

Expected value after %s

Error message

Expected value after %s

What it means

A non-boolean, non-Void option was given in the '--flag value' two-token form but no further argument exists to consume as its value. Boolean-syntax options self-default and Void options take no value, so only value-taking options reach the nextArgs.hasNext() check; at end-of-argv the value is missing and this error names the flag token.

Source

Thrown at src/main/java/com/google/devtools/common/options/OptionsParserImpl.java:836

        suggestion = SpellChecker.didYouMean(arg, getAllValidArgs());
      } else {
        suggestion = "";
      }
      throw new OptionsParsingException("Unrecognized option: " + arg + suggestion, arg);
    }

    if (unconvertedValue == null) {
      // Special-case boolean to supply value based on presence of "no" prefix.
      if (lookupResult.definition.usesBooleanValueSyntax()) {
        unconvertedValue = booleanValue ? "1" : "0";
      } else if (lookupResult.definition.getType().equals(Void.class)) {
        // This is expected, Void type options have no args.
      } else if (nextArgs.hasNext()) {
        // "--flag value" form
        unconvertedValue = nextArgs.next();
        commandLineForm.append(" ").append(unconvertedValue);
      } else {
        throw new OptionsParsingException("Expected value after " + arg);
      }
    }

    if (lookupResult.fromFallback) {
      // The option was not found on the current command, but is a valid option for some other
      // command. Ignore it.
      return new ParsedOptionDescriptionOrIgnoredArgs(
          Optional.empty(), Optional.of(commandLineForm.toString()));
    }

    return new ParsedOptionDescriptionOrIgnoredArgs(
        Optional.of(
            ParsedOptionDescription.newParsedOptionDescription(
                lookupResult.definition,
                commandLineForm.toString(),
                unconvertedValue,
                new OptionInstanceOrigin(
                    priority,

View on GitHub (pinned to e6e199d060)

Solutions

1. Supply the value, ideally in '=' form to keep the pair atomic: `--platforms=//tools:platform`
2. Fix the generator: when appending a value flag, append name and value together or use the '=' form in one token
3. Check params files / .bazelrc for a final line that is a bare value-taking flag

Example fix

# before
bazel build --platforms //...
# after
bazel build --platforms=//tools:default_platform //...

# Ensure value flags always carry '=' so a missing value is impossible
emit() { case "$1" in --*=*) ;; --*) echo "flag '$1' needs =value" >&2; exit 2;; esac; printf '%s ' "$1"; }

When it happens

Trigger: Ending the command line with a value-taking flag: `bazel build //... --platforms`, or a params file whose last line is a bare flag; truncating an argv array mid pair.

Common situations: Scripts appending flags conditionally where the value append is skipped; params files edited by hand leaving the last flag valueless; shell line continuation breaking after the flag token.

Related errors

• A params file must be the only argument: %s
• Error reading params file: %s %s
• Malformed value of --invocation_policy:
• Tried to expand option too many times
• Unrecognized arguments:

AI-assisted analysis of bazelbuild/bazel@e6e199d060 (2026-08-14). Data as JSON: /api/errors/8399179739e7b8a7. Report an issue: GitHub.