languagetool-org/languagetool · error · IllegalStateException

'<marker>' may not be nested in rule '" + id + "'

Error message

'<marker>' may not be nested in rule '" + id + "'

What it means

SAX handler validation of disambiguation rule XML: a <marker> element appears inside another <marker> in an example, which cannot be represented since a marker denotes a single highlighted span. Fires at parse time of the disambiguation.xml for the offending rule.

Source

Thrown at languagetool-core/src/main/java/org/languagetool/tagging/disambiguation/rules/DisambiguationRuleHandler.java:269

          untouchedExamples = new ArrayList<>();
        }
        if (disambExamples == null) {
          disambExamples = new ArrayList<>();
        }
        untouched = attrs.getValue(TYPE).equals("untouched");
        if (attrs.getValue(TYPE).equals("ambiguous")) {
          input = attrs.getValue("inputform");
          output = attrs.getValue("outputform");
        }
        example = new StringBuilder();
        break;
      case "filter":
        filterClassName = attrs.getValue("class");
        filterArgs = attrs.getValue("args");
        break;
      case MARKER:
        if (inMarker) {
          throw new IllegalStateException("'<marker>' may not be nested in rule '" + id + "'");
        }
        example.append("<marker>");
        if (inPattern || inAntiPattern) {
          startPos = tokenCounter;
          inMarker = true;
        }
        break;
    }
  }

  private void refNumberSanityCheck(int refNumber) throws SAXException {
    if (refNumber > patternTokens.size()) {
      throw new SAXException("Only backward references in match elements are possible, tried to specify token "
              + refNumber + "\n Line: " + pLocator.getLineNumber()
              + ", column: " + pLocator.getColumnNumber() + ".");
    }
  }

View on GitHub (pinned to 2e990059ce)

Solutions

1. Remove or unnest the inner <marker> element in the rule's example text
2. Keep at most one marker span per example, marking the matched tokens only

When it happens

Trigger: Thrown at languagetool-core/src/main/java/org/languagetool/tagging/disambiguation/rules/DisambiguationRuleHandler.java:269 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/ab8177c83a80babc. Report an issue: GitHub.