languagetool-org/languagetool · error · IllegalArgumentException

No IssueType found for name '" + name + "'. Valid values: "

Error message

No IssueType found for name '" + name + "'. Valid values: " + Arrays.toString(values())

What it means

ITSIssueType.getIssueType(name) maps a string to one of the ITS issue type enum values; it iterates values() and throws IllegalArgumentException if no enum constant's toString() equals the input. The message lists all valid values.

Source

Thrown at languagetool-core/src/main/java/org/languagetool/rules/ITSIssueType.java:46

 * 
 * @see <a href="http://www.w3.org/International/multilingualweb/lt/drafts/its20/its20.html#lqissue-typevalues">ITS 2.0</a>
 * @since 2.5
 */
public enum ITSIssueType {

  Terminology, Mistranslation, Omission, Untranslated, Addition, Duplication, Inconsistency, Grammar,
  Legal, Register, LocaleSpecificContent("locale-specific-content"), LocaleViolation("locale-violation"),
  Style, Characters, Misspelling, Typographical, Formatting, InconsistentEntities("inconsistent-entities"),
  Numbers, Markup, PatternProblem("pattern-problem"), Whitespace, Internationalization, Length, 
  NonConformance("non-conformance"), Uncategorized, Other;

  public static ITSIssueType getIssueType(String name) {
    for (ITSIssueType issueType : values()) {
      if (issueType.toString().equals(name)) {
        return issueType;
      }
    }
    throw new IllegalArgumentException("No IssueType found for name '" + name + "'. Valid values: " + Arrays.toString(values()));
  }

  private final String name;

  ITSIssueType() {
    this.name = name();
  }

  ITSIssueType(String name) {
    this.name = name;
  }

  /**
   * Use this to get the name as it is used in the ITS 2.0 standard
   * (namely lowercase and with hyphens, not camel case)
   */
  @Override
  public String toString() {

View on GitHub (pinned to 2e990059ce)

Solutions

Compare the input name against the list in the exception message and correct it to an exact, case-sensitive enum name (e.g. 'Uncategorized', 'Grammar', 'Typographical').
Check the rule XML attribute that supplies the name and fix its value.
If the input may be absent or free-form, wrap the call or pre-validate with a whitelist before calling getIssueType.

Example fix

// before
ITSIssueType type = ITSIssueType.getIssueType("grammar");
// after
ITSIssueType type = ITSIssueType.getIssueType("Grammatical");

Defensive patterns

Strategy: validation

Validate before calling

private static final Set<String> VALID = Arrays.stream(ITSIssueType.values())
    .map(Enum::toString).collect(Collectors.toSet());
if (name != null && !VALID.contains(name)) {
  throw new IllegalArgumentException("Unknown ITS issue type: " + name);
}

Type guard

boolean isValidIssueType(String name) {
  return Arrays.stream(ITSIssueType.values()).anyMatch(t -> t.toString().equals(name));
}

Try / catch

try {
  type = ITSIssueType.getIssueType(name);
} catch (IllegalArgumentException e) {
  LOG.warn("Unknown ITS type '{}', defaulting to Uncategorized", name);
  type = ITSIssueType.Uncategorized;
}

Prevention

Validate rule XML against LT's schema before loading
Use enum values via IDE autocompletion instead of typing strings
Note the lookup is case-sensitive — normalize input casing at the source

When it happens

Trigger: Calling ITSIssueType.getIssueType("...") with a name that is not exactly one of the enum constants (case-sensitive), typically a value read from an XML rule attribute (its:type).

Common situations: Typos or wrong casing in rule XML (e.g. 'grammar' vs 'Grammatical'), using free-form text instead of the ITS spec values, or mapping external categories to ITS types with values the library doesn't define.

Understand the failure class

Background: Invalid enum value errors: "Unknown type", "Invalid scope", "must be one of" — when a string is not on the library's allowed list — this error's family across 23 libraries.

Related errors

AI-assisted analysis of languagetool-org/languagetool@2e990059ce (2026-09-06). Data as JSON: /api/errors/7e0dbc35868d98e7. Report an issue: GitHub.