languagetool-org/languagetool · error · NullPointerException

disambiguated POS cannot be null with posSelect == null and

Error message

disambiguated POS cannot be null with posSelect == null and " + disambAction

What it means

Constructor invariant check for DisambiguationPatternRule: an action that needs a replacement POS (e.g. REPLACE) was requested, but both disambiguatedPOS and posSelect are null, so there is no POS to apply. This is an API misuse guard — rule XML is normally validated earlier, so it fires mostly when building rules programmatically.

Source

Thrown at languagetool-core/src/main/java/org/languagetool/tagging/disambiguation/rules/DisambiguationPatternRule.java:76

   * @param description Description to be shown (name)
   * @param disambAction the action to be executed on found token(s)
   * @since public since 2.5
   */
  public DisambiguationPatternRule(String id, String description,
                                   Language language, List<PatternToken> patternTokens,
                                   String disambiguatedPOS, Match posSelect,
                                   DisambiguatorAction disambAction) {
    super(id, description, language, patternTokens, true);
    if (disambiguatedPOS == null && posSelect == null
        && disambAction != DisambiguatorAction.UNIFY
        && disambAction != DisambiguatorAction.ADD
        && disambAction != DisambiguatorAction.REMOVE
        && disambAction != DisambiguatorAction.IMMUNIZE
        && disambAction != DisambiguatorAction.REPLACE
        && disambAction != DisambiguatorAction.FILTERALL
        && disambAction != DisambiguatorAction.IGNORE_SPELLING
        && disambAction != DisambiguatorAction.ADDCHUNK) {
      throw new NullPointerException("disambiguated POS cannot be null with posSelect == null and " + disambAction);
    }
    this.disambiguatedPOS = disambiguatedPOS;
    this.matchElement = posSelect;
    this.disAction = Objects.requireNonNull(disambAction);
    setMessage("");
    suggestionsOutMsg = "";
  }

  /**
   * Used to add new interpretations.
   * @param newReadings
   *          An array of AnalyzedTokens. The length of the array should be the
   *          same as the number of the tokens matched and selected by
   *          {@code <marker>...</marker>} elements.
   */
  public final void setNewInterpretations(AnalyzedToken[] newReadings) {
    newTokenReadings = newReadings.clone();
  }

View on GitHub (pinned to 2e990059ce)

Solutions

1. Provide a non-null disambiguatedPOS or a posSelect Match when using a POS-modifying action
2. Use the correct DisambiguatorAction (e.g. UNIFY or IGNORE) when no POS replacement is intended
3. Fix the rule XML so the action element carries its postag or match attribute

When it happens

Trigger: Thrown at languagetool-core/src/main/java/org/languagetool/tagging/disambiguation/rules/DisambiguationPatternRule.java:76 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of languagetool-org/languagetool@2e990059ce (2026-09-06). Data as JSON: /api/errors/cf2ac0c74adfb3bc. Report an issue: GitHub.