languagetool-org/languagetool · error · IllegalArgumentException

You cannot apply suggestions when tagging only

Error message

You cannot apply suggestions when tagging only

What it means

parseOptions() rejects combining `-t/--taggeronly` with `-a/--apply` (applySuggestions). When --taggeronly is parsed and applySuggestions was already enabled, it throws this IllegalArgumentException: tagging alone cannot rewrite the text with correction suggestions.

Source

Thrown at languagetool-commandline/src/main/java/org/languagetool/commandline/CommandLineParser.java:69

        options.setLineByLine(true);
      } else if (args[i].equals("--enable-temp-off")) {
        options.setEnableTempOff(true);
      } else if (args[i].equals("--clean-overlapping")) {
        options.setCleanOverlapping(true);
      } else if (args[i].equals("--level")) {
        String level = args[++i];
        try {
          options.setLevel(JLanguageTool.Level.valueOf(level));
        } catch (IllegalArgumentException e) {
          throw new IllegalArgumentException("Unknown level '" + level + "' - currently, only 'PICKY' is supported");
        }
      } else if (args[i].equals("-t") || args[i].equals("--taggeronly")) {
        options.setTaggerOnly(true);
        if (options.isListUnknown()) {
          throw new IllegalArgumentException("You cannot list unknown words when tagging only");
        }
        if (options.isApplySuggestions()) {
          throw new IllegalArgumentException("You cannot apply suggestions when tagging only");
        }
      } else if (args[i].equals("-r") || args[i].equals("--recursive")) {
        options.setRecursive(true);
      } else if (args[i].equals("-b2") || args[i].equals("--bitext")) {
        options.setBitext(true);
      } else if (args[i].equals("-eo") || args[i].equals("--enabledonly")) {
        if (options.getDisabledRules().size() > 0) {
          throw new IllegalArgumentException("You cannot specify both disabled rules and enabledonly");
        }
        options.setUseEnabledOnly();
      } else if (args[i].equals("-d") || args[i].equals("--disable")) {
        if (options.isUseEnabledOnly()) {
          throw new IllegalArgumentException("You cannot specify both disabled rules and enabledonly");
        }
        checkArguments("-d/--disable", i, args);
        String rules = args[++i];
        options.setDisabledRules(Arrays.asList(rules.split(",")));
      } else if (args[i].equals("-e") || args[i].equals("--enable")) {

View on GitHub (pinned to 2e990059ce)

Solutions

  1. Drop -t/--taggeronly to allow applying suggestions.
  2. Drop -a/--apply if tag-only output is what you need.
  3. Run two invocations: one to tag, one to apply.

Example fix

// before
languagetool -a -t -l en file.txt
// after
languagetool -a -l en file.txt
Defensive patterns

Strategy: validation

Validate before calling

List<String> a = Arrays.asList(args);
boolean tagOnly = a.contains("-t") || a.contains("--taggeronly");
boolean apply = a.contains("-a") || a.contains("--apply");
if (tagOnly && apply) throw new IllegalArgumentException("-t and -a are mutually exclusive");

Try / catch

try {
  new CommandLineParser().parseOptions(args);
} catch (IllegalArgumentException e) {
  if (e.getMessage().contains("apply suggestions when tagging only")) {
    System.err.println("Choose either -a/--apply or -t/--taggeronly, not both.");
  }
}

Prevention

When it happens

Trigger: `languagetool -a -t file.txt` — --apply parsed first, then --taggeronly sees options.isApplySuggestions() == true.

Common situations: Users wanting both automatic fixes and fast tag-only runs; scripts appending flags from different profiles.

Understand the failure class

Background: "mutually exclusive" flag errors: what "can't supply both nx and xx", "--raw is not compatible with -i" and "cannot be used with" mean, and how to fix them — this error's family across 29 libraries.

Related errors

AI-assisted analysis of languagetool-org/languagetool@2e990059ce (2026-09-06). Data as JSON: /api/errors/9100efd68273f1c1. Report an issue: GitHub.