languagetool-org/languagetool · error · UnsupportedOperationException

Words can't start with " + SUFFIX_MARKER

Error message

Words can't start with " + SUFFIX_MARKER

What it means

Data-integrity guard while grouping the loaded mapping by hash: a lemma in the synthesizer data begins with the reserved SUFFIX_MARKER character, which the encoding uses internally to distinguish suffixed forms and therefore can never appear at the start of a word. The faulty input is the offending lemma string in the synthesizer data file.

Source

Thrown at languagetool-core/src/main/java/org/languagetool/synthesis/ManualSynthesizer.java:114

      }
    });

    possibleTags = Collections.unmodifiableSet(collectTags(mapping));
  }

  private static Int2ObjectOpenHashMap<List<Triple<String, String, String>>> groupByHash(Map<TaggedWord, List<String>> mapping) {
    Int2ObjectOpenHashMap<List<Triple<String, String, String>>> byHash = new Int2ObjectOpenHashMap<>(mapping.size());
    for (Map.Entry<TaggedWord, List<String>> entry : mapping.entrySet()) {
      TaggedWord tw = entry.getKey();
      String lemma = tw.getLemma();
      int hash = hashCode(lemma, tw.getPosTag());
      List<Triple<String, String, String>> list = byHash.get(hash);
      if (list == null) {
        byHash.put(hash, list = new ArrayList<>());
      }
      for (String word : entry.getValue()) {
        if (word.startsWith(SUFFIX_MARKER)) {
          throw new UnsupportedOperationException("Words can't start with " + SUFFIX_MARKER);
        }
        String value = intern(encodeForm(lemma, word));
        list.add(new ImmutableTriple<>(lemma, tw.getPosTag(), value));
      }
    }
    return byHash;
  }

  private static String encodeForm(String lemma, String word) {
    if (word.length() > lemma.length() && word.startsWith(lemma)) {
      return SUFFIX_MARKER + word.substring(lemma.length());
    }
    if (word.length() >= lemma.length() && word.startsWith(lemma.substring(0, lemma.length() - 1))) {
      return SUFFIX_MARKER + SUFFIX_MARKER + word.substring(lemma.length() - 1);
    }
    return word;
  }

View on GitHub (pinned to 2e990059ce)

Solutions

1. Remove or escape the leading SUFFIX_MARKER character in the offending lemma entry of the data file
2. Fix the data-generation step that produced a lemma starting with the reserved marker

When it happens

Trigger: Thrown at languagetool-core/src/main/java/org/languagetool/synthesis/ManualSynthesizer.java:114 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of languagetool-org/languagetool@2e990059ce (2026-09-06). Data as JSON: /api/errors/ff3a675d9e6bbf78. Report an issue: GitHub.