languagetool-org/languagetool · error · RuntimeException

Translation language (

Error message

Translation language (

What it means

When parsing false-friend XML, the handler requires that a rule's translation language differs from the pattern language when running in test mode. If a <translation lang="..."> names the same language as the rule's own language, it throws this RuntimeException — such a rule would compare a language with itself, which is meaningless for false friends.

Source

Thrown at languagetool-core/src/main/java/org/languagetool/rules/patterns/FalseFriendRuleHandler.java:106

      }
      correctExamples = new ArrayList<>();
      incorrectExamples = new ArrayList<>();
    } else if (qName.equals(PATTERN)) {
      inPattern = true;
      String languageStr = attrs.getValue("lang");
      if (Languages.isLanguageSupported(languageStr)) {
        language = Languages.getLanguageForShortCode(languageStr);
      }
    } else if (qName.equals(TOKEN)) {
      setToken(attrs);
    } else if (qName.equals(TRANSLATION)) {
      inTranslation = true;
      String languageStr = attrs.getValue("lang");
      if (Languages.isLanguageSupported(languageStr)) {
        Language tmpLang = Languages.getLanguageForShortCode(languageStr);
        currentTranslationLanguage = tmpLang;
        if (inTestMode && currentTranslationLanguage == language) {
          throw new RuntimeException("Translation language (" + currentTranslationLanguage + ") must not be the same as pattern language (" + language + ") for rule " + id);
        }
        if (tmpLang.equalsConsiderVariantsIfSpecified(motherTongue)) {
          translationLanguage = tmpLang;
        }
      }
    } else if (qName.equals(EXAMPLE)) {
      correctExample = new StringBuilder();
      incorrectExample = new StringBuilder();
      if (attrs.getValue(TYPE).equals("incorrect")) {
        inIncorrectExample = true;
      } else if (attrs.getValue(TYPE).equals("correct")) {
        inCorrectExample = true;
      } else if (attrs.getValue(TYPE).equals("triggers_error")) {
        throw new RuntimeException("'triggers_error' is not supported for false friend XML");
      }
    } else if (qName.equals(MESSAGE)) {
      inMessage = true;
      message = new StringBuilder();

View on GitHub (pinned to 2e990059ce)

Solutions

1. Change the <translation lang="..."> value to a language different from the pattern language
2. Remove the redundant translation element if it doesn't represent a real false-friend pair
3. Check the false-friends.xml diff that introduced the duplicate language and correct it

Example fix

// before
<rule id="FRIEND_EN" ...> <!-- pattern lang="en" -->
  <translation lang="en">tip</translation>
// after
<rule id="FRIEND_EN" ...> <!-- pattern lang="en" -->
  <translation lang="de">Tip</translation>

if (translationLang.equals(patternLang)) {
  throw new IllegalArgumentException("Translation lang must differ from pattern lang");
}

try {
  rules = loader.getRules(file, language, motherTongue);
} catch (RuntimeException e) {
  if (e.getMessage().startsWith("Translation language (")) {
    throw new IOException("Invalid false-friend XML: " + e.getMessage(), e);
  }
  throw e;
}

When it happens

Trigger: Parsing a false-friend XML file (e.g. src/main/resources/org/languagetool/rules/false-friends.xml) in test mode where a <translation> element's lang attribute equals the rule/pattern language, e.g. an 'en' pattern with an 'en' translation.

Common situations: Adding a new false-friend entry and accidentally duplicating the source language in a translation element; copying a translation block and forgetting to change its lang code.

Understand the failure class

Background: "Invalid value" and "allowed values are" config errors: what your library rejected and how to fix it — this error's family across 41 libraries.

Related errors

• ApostropheTypeFilter: Index out of bounds in
• 'triggers_error' is not supported for false friend XML
• Rule group
• No rules are active. Please make sure your rule ids (<option
• List of language models is empty

AI-assisted analysis of languagetool-org/languagetool@2e990059ce (2026-09-06). Data as JSON: /api/errors/20ffad898d804441. Report an issue: GitHub.