languagetool-org/languagetool · error · IOException

Format error in file " + path + ", line: " + line

Error message

Format error in file " + path + ", line: " + line

What it means

WordCoherencyDataLoader.loadWords reads a coherency data file where each line must contain exactly two semicolon-separated fields ('word;word'). This IOException is thrown for any non-empty, non-comment line that does not split into exactly 2 parts.

Source

Thrown at languagetool-core/src/main/java/org/languagetool/rules/WordCoherencyDataLoader.java:52

 * @since 3.0
 */
public class WordCoherencyDataLoader {

  public Map<String, Set<String>> loadWords(String path) {
    InputStream stream = JLanguageTool.getDataBroker().getFromRulesDirAsStream(path);
    Map<String, Set<String>> map = new Object2ObjectOpenHashMap<>();
    try (
      InputStreamReader reader = new InputStreamReader(stream, StandardCharsets.UTF_8);
      BufferedReader br = new BufferedReader(reader)
    ) {
      String line;
      while ((line = br.readLine()) != null) {
        if (line.isEmpty() || line.charAt(0) == '#') {   // ignore comments
          continue;
        }
        String[] parts = line.split(";");
        if (parts.length != 2) {
          throw new IOException("Format error in file " + path + ", line: " + line);
        }
        if(map.containsKey(parts[0])) {
          map.get(parts[0]).add(parts[1]);
        } else {
          map.put(parts[0], Stream.of(parts[1]).collect(Collectors.toCollection(ObjectOpenHashSet::new)));
        }
        if(map.containsKey(parts[1])) {
          map.get(parts[1]).add(parts[0]);
        } else {
          map.put(parts[1], Stream.of(parts[0]).collect(Collectors.toCollection(ObjectOpenHashSet::new)));
        }
      }
    } catch (IOException e) {
      throw new RuntimeException("Could not load coherency data from " + path, e);
    }
    return Collections.unmodifiableMap(map);
  }

View on GitHub (pinned to 2e990059ce)

Solutions

  1. Locate the offending line (printed in the exception message) in the file at 'path'.
  2. Ensure it has exactly one semicolon separating the two forms, e.g. 'color;colour'.
  3. Remove extra semicolons or fix a wrong separator (e.g. ',' -> ';').

Example fix

// before (data file)
color:colour
// after (data file)
color;colour
Defensive patterns

Strategy: validation

Validate before calling

// validate coherency data lines before loading
for (String line : Files.readAllLines(Paths.get(path))) {
    if (line.isEmpty() || line.startsWith("#")) continue;
    if (line.split(";", -1).length != 2)
        throw new IllegalStateException("Bad coherency line: " + line);
}

Try / catch

try { loader.loadWords(path, language); } catch (IOException e) { log.error("Coherency data format error: " + e.getMessage()); throw new UncheckedIOException(e); }

Prevention

When it happens

Trigger: Calling loadFromPath/loadWords on a coherency file containing a line with zero or multiple semicolons, e.g. 'word' or 'a;b;c' (no comments allowed except lines starting with '#').

Common situations: Misspelled separator (comma or tab instead of semicolon); trailing semicolon on a line; contributors editing language coherency data by hand.

Understand the failure class

Background: "Invalid ... format", "must be in format X", "does not look like a ..." — invalid argument format errors across CLI tools and libraries — this error's family across 17 libraries.

Related errors

AI-assisted analysis of languagetool-org/languagetool@2e990059ce (2026-09-06). Data as JSON: /api/errors/a96b3487356bf426. Report an issue: GitHub.