languagetool-org/languagetool · error · RuntimeException

URL does not seem to be a valid Wikipedia URL: + url

Error message

URL does not seem to be a valid Wikipedia URL: + url

What it means

WikipediaQuickCheck validates the given URL against regular expressions for regular and secure (https) Wikipedia URLs. If neither matches, getUrlMatcher throws a RuntimeException stating the URL does not look like a valid Wikipedia URL.

Source

Thrown at languagetool-wikipedia/src/main/java/org/languagetool/dev/wikipedia/WikipediaQuickCheck.java:111

  public Language getLanguage(URL url) {
    Matcher matcher = getUrlMatcher(url.toString());
    return Languages.getLanguageForShortCode(matcher.group(1));
  }

  public String getPageTitle(URL url) {
    Matcher matcher = getUrlMatcher(url.toString());
    return matcher.group(2);
  }
  
  private Matcher getUrlMatcher(String url) {
    Matcher matcher1 = WIKIPEDIA_URL_REGEX.matcher(url);
    Matcher matcher2 = SECURE_WIKIPEDIA_URL_REGEX.matcher(url);
    if (matcher1.matches()) {
      return matcher1;
    } else if (matcher2.matches()) {
      return matcher2;
    }
    throw new RuntimeException("URL does not seem to be a valid Wikipedia URL: " + url);
  }

  public void setDisabledRuleIds(List<String> ruleIds) {
    disabledRuleIds = ruleIds;
  }
  
  public List<String> getDisabledRuleIds() {
    return disabledRuleIds;
  }

  public MarkupAwareWikipediaResult checkPage(URL url) throws IOException, PageNotFoundException {
    return checkPage(url, null);
  }

  /**
   * @since 2.6
   */
  public MarkupAwareWikipediaResult checkPage(URL url, ErrorMarker errorMarker) throws IOException, PageNotFoundException {

View on GitHub (pinned to 2e990059ce)

Solutions

1. Use a standard Wikipedia URL of the form http(s)://<lang>.wikipedia.org/...
2. Check for typos in the URL/domain
3. Update the SECURE/regular Wikipedia URL regex patterns to cover the URL form you use
4. Pre-validate the URL against the supported pattern in your own code before calling

Example fix

// before
String url = "https://de.wiktionary.org/wiki/Haus";
// after
String url = "https://de.wikipedia.org/wiki/Haus";

private static final Pattern WIKI = Pattern.compile("https?://[a-z-]+\\.wikipedia\\.org/.*");
if (url == null || !WIKI.matcher(url).matches()) throw new IllegalArgumentException("not a wikipedia URL");

boolean isWikipediaUrl(String url) { return url != null && WIKIPEDIA_URL_REGEX.matcher(url).matches(); }

try {
  Matcher m = quickCheck.getUrlMatcher(url);
} catch (RuntimeException e) {
  System.err.println("Please provide a URL like https://en.wikipedia.org/wiki/...");
}

When it happens

Trigger: Passing a non-Wikipedia URL, a URL with an unexpected host pattern (e.g. wikimedia project other than wikipedia, mobile domain, or missing language subdomain) to the quick-check entry point.

Common situations: Using https://simple.wiktionary.org or another Wikimedia project instead of *.wikipedia.org; typos in the domain; very new domain forms not covered by the bundled regexes.

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

• Got " + matcher.groupCount() + " groups for regex '" + patte
• Got " + matcher.groupCount() + " groups for regex '" + patte
• suppressMisspelledMatch must be a valid regex
• suppressMisspelledSuggestions must be a valid regex
• Error analyzing sentence: '${sentence}' with rule ${rule.get

AI-assisted analysis of languagetool-org/languagetool@2e990059ce (2026-09-06). Data as JSON: /api/errors/4ccb7e48fe650ce2. Report an issue: GitHub.