languagetool-org/languagetool · error · IllegalStateException

Neither '<pattern>' tokens nor '<regexp>' is set in rule '

Error message

Neither '<pattern>' tokens nor '<regexp>' is set in rule '

What it means

A <rule> body must define either a <pattern> (token list) or a <regexp>. If neither was parsed by the time createRules builds the rule, it throws this IllegalStateException — the rule has no matchable content.

Source

Thrown at languagetool-core/src/main/java/org/languagetool/rules/patterns/PatternRuleHandler.java:799

        rule.setXmlLineNumber(xmlLineNumber);
      } else if (regex.length() > 0) {
        // UNICODE_CHARACTER_CLASS (equivalent to the inline (?U) flag) makes \b, \w, \d and \s
        // Unicode-aware. Without it the behavior of word boundaries next to non-ASCII letters
        // depends on the JDK version (it changed between JDK 17 and JDK 21), which breaks many
        // <regexp> rules. Setting it here avoids adding (?U) by hand to every <regexp> pattern.
        int flags = Pattern.UNICODE_CHARACTER_CLASS | (regexCaseSensitive ? 0 : Pattern.CASE_INSENSITIVE|Pattern.UNICODE_CASE);
        String regexStr = regex.toString();
        if (regexMode == RegexpMode.SMART) {
          // Note: it's not that easy to add \b because the regex might look like '(foo)' or '\d' so we cannot just look at the last character
          regexStr = replaceSpacesInRegex(regexStr);
        }
        if (ruleAntiPatterns.size() > 0 || rulegroupAntiPatterns.size() > 0) {
          throw new RuntimeException("<regexp> rules currently cannot be used together with <antipattern>. Rule id: " + id + "[" + subId + "]");
        }
        rule = new RegexPatternRule(id, name, message.toString(), shortMessage, suggestionsOutMsg.toString(), language, Pattern.compile(regexStr, flags), regexpMark);
        rule.setSourceFile(sourceFile);
      } else {
        throw new IllegalStateException("Neither '<pattern>' tokens nor '<regexp>' is set in rule '" + id + "'");
      }
      setRuleFilter(filterClassName, filterArgs, rule);
      prepareRule(rule);
      rules.add(rule);
    } else {
      PatternToken patternToken = elemList.get(numElement);
      if (patternToken.hasOrGroup()) {
        // When creating a new rule, we finally clear the backed-up variables. All the elements in
        // the OR group should share the values of backed-up variables. That's why these variables
        // are backed-up.
        List<Match> suggestionMatchesBackup = new ArrayList<>(suggestionMatches);
        List<Match> suggestionMatchesOutMsgBackup =  new ArrayList<>(suggestionMatchesOutMsg);
        int startPosBackup = startPos;
        int endPosBackup = endPos;
        List<DisambiguationPatternRule> ruleAntiPatternsBackup = new ArrayList<>(ruleAntiPatterns);
        for (PatternToken patternTokenOfOrGroup : patternToken.getOrGroup()) {
          List<PatternToken> tmpElements2 = new ArrayList<>();
          tmpElements2.addAll(tmpPatternTokens);

View on GitHub (pinned to 2e990059ce)

Solutions

1. Add a <pattern> element with at least one <token> to the rule
2. Or add a <regexp> element with the regex to match
3. Check the element spelling/casing — it must be exactly <pattern> or <regexp>

Example fix

// before
<rule id="X" name="x"><message>...</message></rule>
// after
<rule id="X" name="x"><pattern><token>foo</token></pattern><message>...</message></rule>

// Ensure each rule has a pattern or regexp body
NodeList rules = doc.getElementsByTagName("rule");
for (int i = 0; i < rules.getLength(); i++) {
  Element r = (Element) rules.item(i);
  if (r.getElementsByTagName("pattern").getLength() == 0 && r.getElementsByTagName("regexp").getLength() == 0)
    throw new IllegalStateException("rule without pattern/regexp: " + r.getAttribute("id"));
}

try { loader.parse(ruleXml, lang); } catch (IllegalStateException e) { if (e.getMessage().contains("Neither '<pattern>' tokens nor '<regexp>'")) { log.error("Add a <pattern> or <regexp> to the rule"); } throw e; }

When it happens

Trigger: Parsing a rule XML where the rule element contains no <pattern> tokens and no <regexp> child; createRules is invoked from endElement when the rule closes.

Common situations: Skeleton/template rule XML left unfilled; XML where the pattern block was accidentally deleted or misnamed (e.g. <patterns>); typos in element names.

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

• id is null for rule with name '
• Cannot activate rule '
• '<marker>' may not be nested in rule '
• <antipattern>s can only contain <example>s without errors (i
• <regexp> rules currently cannot be used together with <antip

AI-assisted analysis of languagetool-org/languagetool@2e990059ce (2026-09-06). Data as JSON: /api/errors/95ba8e16250aadaa. Report an issue: GitHub.