languagetool-org/languagetool · error · RuntimeException

Could not parse URL for rule

Error message

Could not parse URL for rule: ${rule}: '${urlForRuleGroup}'

What it means

Same URL guard but for the rule-group-level url: when a rule defines no url of its own, urlForRuleGroup is inherited and parsed. If that inherited value is malformed, prepareRule throws this RuntimeException naming the rule and the group URL.

Solutions

1. Fix the url attribute on the <rulegroup> element (add scheme / encode characters)
2. Or give the rule its own valid url attribute to override the broken inherited one
3. Remove the group url attribute if the link is obsolete

Example fix

// before
<rulegroup id="G" url="wiki page">
// after
<rulegroup id="G" url="https://example.com/wiki/page">

// Validate rulegroup-level url attributes before loading
NodeList groups = doc.getElementsByTagName("rulegroup");
for (int i = 0; i < groups.getLength(); i++) {
  Node u = groups.item(i).getAttributes().getNamedItem("url");
  if (u != null) new java.net.URL(u.getNodeValue());
}

try { loader.parse(ruleXml, lang); } catch (RuntimeException e) { if (e.getMessage().contains("Could not parse URL for rule")) { log.error("Fix rulegroup url attribute"); } throw e; }

When it happens

Trigger: A <rule> with no url attribute inside a <rulegroup url="..."> where the group URL fails java.net.URL parsing.

Common situations: Group-level URL written without scheme or with illegal characters; several rules failing at once because one bad group URL is inherited by every subrule.

Understand the failure class

Background: "Invalid URL" errors: why new URL(), URI.parse, and reqwest::Url reject your string — missing scheme, whitespace, and bad path format — this error's family across 39 libraries.

Related errors

• Could not parse URL for rule:
• s can only contain s without errors (i.e. no…
• Cannot activate rule '
• id is null for rule with name '
• MalformedURLException for decommunization URL

AI-assisted analysis of languagetool-org/languagetool@2e990059ce (2026-09-06). Data as JSON: /api/errors/f163e6c437cfbc73. Report an issue: GitHub.

Appendix: source

Thrown at languagetool-core/src/main/java/org/languagetool/rules/patterns/PatternRuleHandler.java:924

    }
    if (defaultOff) {
      rule.setDefaultOff();
    }
    if (defaultTempOff) {
      rule.setDefaultTempOff();
    }
    if (url != null && url.length() > 0) {
      try {
        String s = url.toString();
        rule.setUrl(internUrl(s));
      } catch (MalformedURLException e) {
        throw new RuntimeException("Could not parse URL for rule: " + rule + ": '" + url + "'", e);
      }
    } else if (urlForRuleGroup != null && urlForRuleGroup.length() > 0) {
      try {
        rule.setUrl(internUrl(urlForRuleGroup.toString()));
      } catch (MalformedURLException e) {
        throw new RuntimeException("Could not parse URL for rule: " + rule + ": '" + urlForRuleGroup + "'", e);
      }
    }
    // inheritance of values - if no type value is defined for a rule, take the rule group's value etc:
    if (ruleIssueType != null) {
      rule.setLocQualityIssueType(ITSIssueType.getIssueType(ruleIssueType));
    } else if (ruleGroupIssueType != null) {
      rule.setLocQualityIssueType(ITSIssueType.getIssueType(ruleGroupIssueType));
    } else if (categoryIssueType != null) {
      rule.setLocQualityIssueType(ITSIssueType.getIssueType(categoryIssueType));
    }
    int prio = 0;
    if (prioCategoryAttribute != 0) {
      prio = prioCategoryAttribute;
    }
    if (prioRuleGroupAttribute != 0) {
      prio = prioRuleGroupAttribute;
    }
    if (prioRuleAttribute != 0) {

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