languagetool-org/languagetool · error · IllegalArgumentException

Unknown authMethod

Error message

Unknown authMethod: <authParameter>

What it means

The optional 'authMethod' query parameter of /v2/users/me must be one of 'password', 'apiKey', or 'addonToken'; any other value makes handleGetUserInfoRequest throw an IllegalArgumentException listing the offending value. It tells the server how to interpret the password part of the Basic auth credentials.

Solutions

1. Set authMethod to one of exactly: password, apiKey, addonToken (case-sensitive).
2. Omit the authMethod parameter entirely to use the default 'password'.
3. Fix casing: 'apiKey' with a capital K, not 'apikey' or 'api_key'.

Example fix

// before
GET /v2/users/me?authMethod=apikey
// after
GET /v2/users/me?authMethod=apiKey

const ALLOWED = ['password', 'apiKey', 'addonToken'];
if (authMethod && !ALLOWED.includes(authMethod)) throw new Error(`authMethod must be one of ${ALLOWED.join(', ')}`);

function isValidAuthMethod(v) {
  return v === undefined || ['password', 'apiKey', 'addonToken'].includes(v);
}

When it happens

Trigger: GET /v2/users/me?authMethod=oauth (unsupported value); typo like 'apikey' vs 'apiKey'; client library emitting an auth method this server version does not know.

Common situations: Newer/older client-server version mismatches where one side supports an auth method the other doesn't; hand-written query strings with wrong casing.

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

• Expected Basic Authentication
• 'lang' parameter missing
• Missing 'text' or 'data' parameter
• 'ruleId' parameter missing
• apiKey AND password was set, set only apiKey

AI-assisted analysis of languagetool-org/languagetool@2e990059ce (2026-09-06). Data as JSON: /api/errors/8212735f01d0c419. Report an issue: GitHub.

Appendix: source

Thrown at languagetool-server/src/main/java/org/languagetool/server/ApiV2.java:366

    if (httpExchange.getRequestMethod().equalsIgnoreCase("options")) {
      ServerTools.setAllowOrigin(httpExchange, allowOriginUrl);
      httpExchange.getResponseHeaders().put("Access-Control-Allow-Methods", Collections.singletonList("GET, OPTIONS"));
      List<String> requestHeaders = httpExchange.getRequestHeaders().get("Access-Control-Request-Headers");
      if (requestHeaders != null) {
        httpExchange.getResponseHeaders().put("Access-Control-Allow-Headers", Collections.singletonList(String.join(", ", requestHeaders)));
      }
      httpExchange.sendResponseHeaders(HttpURLConnection.HTTP_NO_CONTENT, -1);
      ServerMetricsCollector.getInstance().logResponse(HttpURLConnection.HTTP_NO_CONTENT);
    } else {
      ensureGetMethod(httpExchange, "/users/me");
      if (!httpExchange.getRequestHeaders().containsKey("Authorization")) {
        throw new AuthException("Expected Basic Authentication");
      }
      String authParameter = parameters.getOrDefault("authMethod", "password");
      if (!(authParameter.equals("password") || 
            authParameter.equals("apiKey") || 
            authParameter.equals("addonToken"))) {
        throw new IllegalArgumentException("Unknown authMethod: " + authParameter);
      }

      String authHeader = httpExchange.getRequestHeaders().getFirst("Authorization");
      BasicAuthentication basicAuthentication = new BasicAuthentication(authHeader);
      String user = basicAuthentication.getUser();
      String password = basicAuthentication.getPassword();
      UserInfoEntry userInfo = null;

      if (authParameter.equals("password")) {
        userInfo = DatabaseAccess.getInstance().getUserInfoWithPassword(user, password);
      } else if (authParameter.equals("addonToken")) {
        userInfo = DatabaseAccess.getInstance().getUserInfoWithAddonToken(user, password);
      } else if (authParameter.equals("apiKey")) {
        userInfo = DatabaseAccess.getInstance().getUserInfoWithApiKey(user, password);
      }

      String format = parameters.getOrDefault("format", "extended");
      if (userInfo != null) {

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