languagetool-org/languagetool · error · RuntimeException

Rule group

Error message

Rule group 

What it means

In pattern-rule XML, minPrevMatches may be set on a <rulegroup> or on individual <rule> elements, not both in a conflicting way. If a rule declares minPrevMatches while its rule group already set it to a value > 0, PatternRuleHandler.startElement throws this RuntimeException to prevent ambiguous inheritance.

Solutions

1. Remove the minPrevMatches attribute from the inner <rule> and rely on the rulegroup value
2. Or remove it from the <rulegroup> if the per-rule values are intended to differ
3. Search the XML for rules inside groups that both define minPrevMatches and resolve the duplication

Example fix

// before
<rulegroup id="G" minPrevMatches="2">
  <rule id="R1" minPrevMatches="1">...
// after
<rulegroup id="G" minPrevMatches="2">
  <rule id="R1">...

if (ruleGroupMinPrevMatches > 0 && rule.hasAttribute("minPrevMatches")) {
  throw new IllegalArgumentException("minPrevMatches set on both rulegroup and rule");
}

try {
  rules = handler.getRules(stream, filename);
} catch (RuntimeException e) {
  if (e.getMessage().contains(MINPREVMATCHES)) {
    log.error("Remove duplicate minPrevMatches in rule XML: {}", e.getMessage());
  }
  throw e;
}

When it happens

Trigger: Parsing pattern rule XML where <rulegroup minPrevMatches="2"> contains a <rule minPrevMatches="..."> — i.e. the attribute is specified at both levels.

Common situations: Merging rule XML files or copying rules between groups, moving minPrevMatches to the group but leaving it on child rules (or vice versa), and bulk edits that duplicate the attribute.

Understand the failure class

Background: Conflicting config options: "cannot be used together" — configuration validation errors across open-source libraries — this error's family across 162 libraries.

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• AbstractAdvancedSynthesizerFilter only works with pattern…
• Cannot use --premiumAlways with non-premium version
• code is supposed to be a 2 (or rarely 3) character code…

AI-assisted analysis of languagetool-org/languagetool@2e990059ce (2026-09-06). Data as JSON: /api/errors/2cd1183759efad05. Report an issue: GitHub.

Appendix: source

Thrown at languagetool-core/src/main/java/org/languagetool/rules/patterns/PatternRuleHandler.java:179

        inRegex = true;
        regexMode = "exact".equals(attrs.getValue("type")) ? RegexpMode.EXACT : RegexpMode.SMART;
        regexCaseSensitive = attrs.getValue(CASE_SENSITIVE) != null && YES.equals(attrs.getValue(CASE_SENSITIVE));
        regexpMark = attrs.getValue(MARK) != null ? Integer.parseInt(attrs.getValue(MARK)) : 0;
        break;
      case RULE:
        xmlLineNumber = pLocator.getLineNumber();
        regex = new StringBuilder();
        inRule = true;
        shortMessage = new StringBuilder();
        message = new StringBuilder();
        suggestionsOutMsg = new StringBuilder();
        url = new StringBuilder();
        id = attrs.getValue(ID);
        name = attrs.getValue(NAME);
        String minPrevMatchesStr = attrs.getValue(MINPREVMATCHES);
        if (minPrevMatchesStr != null) {
          if (inRuleGroup && ruleGroupMinPrevMatches > 0) {
            throw new RuntimeException("Rule group " + ruleGroupId + " has " + MINPREVMATCHES + "=" + ruleGroupMinPrevMatches
                + ", thus rule " + id + " cannot specify " + MINPREVMATCHES);
          }
          minPrevMatches = Integer.parseInt(minPrevMatchesStr);  
        } else {
          minPrevMatches = ruleGroupMinPrevMatches;
        }
        String distanceTokensStr = attrs.getValue(DISTANCETOKENS);
        if (distanceTokensStr != null) {
          if (inRuleGroup && ruleGroupDistanceTokens > 0) {
            throw new RuntimeException("Rule group " + ruleGroupId + " has " + DISTANCETOKENS + "=" + ruleGroupDistanceTokens
                + ", thus rule " + id + " cannot specify " + DISTANCETOKENS);
          }
          distanceTokens = Integer.parseInt(distanceTokensStr);  
        } else {
          distanceTokens = ruleGroupDistanceTokens;
        }
        String premiumRule = attrs.getValue(PREMIUM);
        //check if this rule is premium

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