languagetool-org/languagetool · error · RuntimeException

No field '" + fieldName + "' found in doc + match.doc

Error message

No field '" + fieldName + "' found in doc + match.doc

What it means

After fetching a hit document from the Lucene index, findMatchingSentences reads the configured field and throws a RuntimeException if the field is missing (null). The index was built without (or with an empty) value for the requested field, so sentence-level checking cannot proceed.

Source

Thrown at languagetool-wikipedia/src/main/java/org/languagetool/dev/index/Searcher.java:280

    } else {
      throw new PatternRuleNotFoundException(ruleId, language);
    }
  }

  private MatchingSentencesResult findMatchingSentences(IndexSearcher indexSearcher, TopDocs topDocs, JLanguageTool languageTool) throws IOException {
    List<MatchingSentence> matchingSentences = new ArrayList<>();
    int i = 0;
    int docsChecked = 0;
    for (ScoreDoc match : topDocs.scoreDocs) {
      i++;
      if (i < skipHits) {
        // needed for paging
        continue;
      }
      Document doc = indexSearcher.doc(match.doc);
      String sentence = doc.get(fieldName);
      if (sentence == null) {
        throw new RuntimeException("No field '" + fieldName + "' found in doc " + match.doc);
      }
      List<RuleMatch> ruleMatches = languageTool.check(sentence);
      docsChecked++;
      if (ruleMatches.size() > 0) {
        String source = doc.get(SOURCE_FIELD_NAME);
        String title = doc.get(Indexer.TITLE_FIELD_NAME);
        AnalyzedSentence analyzedSentence = languageTool.getAnalyzedSentence(sentence);
        MatchingSentence matchingSentence = new MatchingSentence(sentence, source, title, analyzedSentence, ruleMatches);
        matchingSentences.add(matchingSentence);
      }
    }
    return new MatchingSentencesResult(matchingSentences, i, docsChecked);
  }
  
  static class MatchingSentencesResult {
    List<MatchingSentence> matchingSentences;
    int maxDocChecked;
    int docsChecked;

View on GitHub (pinned to 2e990059ce)

Solutions

1. Rebuild the index so all documents contain the requested field
2. Verify the fieldName argument matches the field used by Indexer during indexing
3. Skip documents missing the field instead of aborting
4. Check the index schema/mappings for null or empty stored fields

Example fix

// before
throw new RuntimeException("No field '" + fieldName + "' found in doc " + match.doc);
// after
if (sentence == null) { LOG.warn("doc " + match.doc + " missing field " + fieldName); continue; }

Document doc = indexSearcher.doc(match.doc);
if (doc.get(fieldName) == null) { skip; }

try {
  result = searcher.findMatchingSentences(...);
} catch (RuntimeException e) {
  if (e.getMessage().startsWith("No field")) { rebuildIndex(); }
}

When it happens

Trigger: A hit document in topDocs lacks the requested field (e.g. the sentence text field); happens when the index was created by an Indexer version/config that stored a different field name.

Common situations: Searching an index built with an older/different Indexer configuration; passing a wrong fieldName; documents skipped during indexing (e.g. empty pages) leaving the field unset.

Understand the failure class

Background: 'Could not be found', 'does not exist', 'not found in database': the resource-not-found family when an ID, slug, key, or URI lookup comes back empty — this error's family across 20 libraries.

Related errors

• Directory must contain at least '1grams', '2grams', and '3gr
• Expected at least '1grams', '2grams', and '3grams' sub direc
• No directories '1grams' ... '3grams' found in ${topIndexDir}
• Requested ${tokens.size()}gram but index has only up to ${ma
• Expected 'totalTokenCount' meta documents not found in 1gram

AI-assisted analysis of languagetool-org/languagetool@2e990059ce (2026-09-06). Data as JSON: /api/errors/7eddadb6aed04e28. Report an issue: GitHub.