apache/druid · error · IllegalArgumentException

Invalid URL format for MySQL: [%s]

Error message

Invalid URL format for MySQL: [%s]

What it means

Thrown by ConnectionUriUtils.tryParseMySqlConnectionUri when the MySQL Connector/J ConnectionUrl class reports acceptsUrl(uri)==false for the given JDBC URI. Druid parses JDBC URIs reflectively to extract host/port/db properties (e.g. for extension metadata), and this check guards against URIs the MySQL driver cannot accept at all.

Source

Thrown at processing/src/main/java/org/apache/druid/utils/ConnectionUriUtils.java:207

    Class<?> driverClass = Class.forName(POSTGRES_DRIVER);
    Method parseUrl = driverClass.getMethod("parseURL", String.class, Properties.class);
    Properties properties = (Properties) parseUrl.invoke(null, connectionUri, null);
    if (properties == null) {
      throw new IAE("Invalid URL format for PostgreSQL: [%s]", connectionUri);
    }
    Set<String> keys = Sets.newHashSetWithExpectedSize(properties.size());
    properties.forEach((k, v) -> keys.add((String) k));
    return keys;
  }

  public static Set<String> tryParseMySqlConnectionUri(String connectionUri)
      throws ClassNotFoundException, NoSuchMethodException, IllegalAccessException,
             InvocationTargetException
  {
    Class<?> connectionUrlClass = Class.forName(MYSQL_CONNECTION_URL);
    Method isConnectionStringSupported = connectionUrlClass.getMethod("acceptsUrl", String.class);
    if (!(boolean) isConnectionStringSupported.invoke(connectionUrlClass, connectionUri)) {
      throw new IAE("Invalid URL format for MySQL: [%s]", connectionUri);
    }
    Method getConnectionUrlInstanceMethod = connectionUrlClass.getMethod("getConnectionUrlInstance", String.class, Properties.class);
    Object conUrl = getConnectionUrlInstanceMethod.invoke(connectionUrlClass, connectionUri, null);
    Method getHostsList = connectionUrlClass.getMethod("getHostsList");
    return getKeysFromOptions(getPropertiesFromHosts((List<?>) getHostsList.invoke(conUrl)));
  }

  private static Properties getPropertiesFromHosts(List<?> hostsList)
      throws NoSuchMethodException, InvocationTargetException, IllegalAccessException, ClassNotFoundException
  {
    Properties properties = new Properties();
    Class<?> hostInfoClass = Class.forName(MYSQL_HOST_INFO);
    for (Object host : hostsList) {
      Method getHostMethod = hostInfoClass.getMethod("getHost");
      String hostName = (String) getHostMethod.invoke(host);
      if (hostName != null) {
        properties.setProperty("HOST", hostName);
      }

View on GitHub (pinned to 9b90983fd2)

Solutions

1. Verify the URI starts with jdbc:mysql:// and follows the documented Connector/J URL syntax
2. Confirm the intended MySQL Connector/J jar is on the classpath and matches the URL dialect
3. Log the full connectionUri and test it with a plain DriverManager.getConnection to see the driver's own complaint
4. If the URI belongs to another database, ensure it is routed to the correct parser, not the MySQL one

Example fix

// before
String uri = "jdbc:mysql//localhost:3306/druid";
// after
String uri = "jdbc:mysql://localhost:3306/druid";

boolean valid = uri != null && uri.startsWith("jdbc:mysql://");
if (valid) {
  try { java.sql.DriverManager.getConnection(uri + (uri.contains("?") ? "&" : "?") + "connectTimeout=1000"); }
  catch (Exception e) { /* driver rejects it */ }
}

static boolean looksLikeMySqlJdbcUri(String uri) {
  return uri != null && uri.regionMatches(true, 0, "jdbc:mysql://", 0, 13);
}

try {
  params = ConnectionUriUtils.tryParseJdbcUriParameters(uri);
} catch (IllegalArgumentException e) {
  if (e.getMessage() != null && e.getMessage().contains("Invalid URL format for MySQL")) {
    log.error("Rejecting malformed MySQL URI: {}", uri, e);
  }
  throw e;
}

When it happens

Trigger: Calling tryParseJdbcUriParameters (directly or via its callers) with a jdbc:mysql: URL that MySQL Connector/J rejects: wrong scheme spelling, missing '//' after jdbc:mysql:, unsupported MySQL X DevAPI forms, or a URI scheme routed to the MySQL parser that is not actually a mysql URL.

Common situations: Typos like 'jdbc:mysql//host:3306/db', copy-pasted URIs from other databases, dynamically built connection strings with empty or malformed host sections, or a mismatched mysql-connector-java version on the classpath that no longer accepts the URL shape.

Understand the failure class

Background: "Invalid URL" errors: why new URL(), URI.parse, and reqwest::Url reject your string — missing scheme, whitespace, and bad path format — this error's family across 39 libraries.

Related errors

• Failed to find MySQL driver class. Please check the MySQL co
• Invalid URL format for MariaDB: [%s]
• JDBC Kerberos auth not supported yet
• JDBC driver JAR files missing from extensions/druid-lookups-
• JDBC driver JAR files missing in the classpath

AI-assisted analysis of apache/druid@9b90983fd2 (2026-09-07). Data as JSON: /api/errors/a31eacc6011bc78f. Report an issue: GitHub.