MySQL Connector/J for Minecraft

Oracle's official MySQL Connector/J repackaged as a Bukkit/Spigot/Paper plugin and a Fabric/Forge/NeoForge mod.

Heads up: CraftBukkit/Spigot/Paper have shipped MySQL Connector/J on the server's parent classloader since 1.4 (the "ebeans" era). For the default JDBC path (Class.forName("com.mysql.cj.jdbc.Driver") / DriverManager.getConnection) the bundled driver wins — installing this mod doesn't change that. This mod is primarily useful on Fabric, NeoForge, and Bukkit forks that strip the bundled driver. If you specifically want this mod's connector instead of the bundled one (e.g. for a newer connector version), use the public API — see Using this mod's connector via the public API below.

What's in the jar

com.mysql:mysql-connector-j:9.1.0 plus minimal loader stubs for Spigot, Forge 1.12, Forge 1.13–1.16, Forge 1.17–1.20, NeoForge 1.21+, and Fabric. No relocation — com.mysql.cj.* classes stay at canonical paths so Class.forName("com.mysql.cj.jdbc.Driver") finds them. META-INF/services/java.sql.Driver is preserved so the driver auto-registers with DriverManager.

The mysql:mysql-connector-java → com.mysql:mysql-connector-j rename happened in connector-j 8.x. The class name com.mysql.cj.jdbc.Driver works across both old and new artifact coords, so the runtime probe is stable.

Compatibility

| Loader | MC versions | Notes | |---|---|---| | Bukkit / Spigot / Paper / Folia / Purpur | 1.8 → current | usually unnecessary — driver is server-bundled | | Fabric | 1.16.1 → current | needs Fabric Loader 0.14+ | | Forge | 1.12 → 1.20 | universal jar, no Mixins | | NeoForge | 1.21 → current | drop into mods/ |

Java 8+ required.

Connection-string gotchas worth knowing

The 5.1.x and 8+ drivers default to behaviours that almost always need overriding for real deployments:

• useSSL=true is the default — fails against any MySQL server without a public CA-signed cert. Set useSSL=false for plaintext, or add verifyServerCertificate=false if you have a self-signed cert.
• caching_sha2_password (MySQL 8 default) needs allowPublicKeyRetrieval=true for unencrypted-channel auth, otherwise the handshake fails with Public Key Retrieval is not allowed.
• rewriteBatchedStatements=true folds JDBC batch INSERTs into multi-row form on the wire. Without it, batch operations are still N round-trips.

Typical URL:

jdbc:mysql://host:3306/db?useSSL=false&allowPublicKeyRetrieval=true&rewriteBatchedStatements=true

MariaDB speaks the MySQL protocol on the wire, so this driver works against MariaDB too. If you want the MariaDB-native connector instead, it's a separate driver and not in scope here.

Versioning

The jar version tracks connector-j one-to-one. 9.1.0+2026-04-25 ships connector-j 9.1.0; the suffix is the build date. A scheduled GitHub Action checks Maven Central daily and bumps automatically.

Using this mod's connector via the public API

If you specifically want this mod's connector instead of the bundled one — to upgrade past a stale fork's bundled driver, or to test a newer connector version — your plugin softdepends on this holder and calls MinecraftMysqlJdbc.connect(url, props):

# in your plugin.yml
softdepend: [mysql-jdbc]

Properties props = new Properties();
props.setProperty("user", "grim");
props.setProperty("password", "...");
Connection c;
try {
    c = MinecraftMysqlJdbc.connect("jdbc:mysql://host:3306/db?useSSL=false", props);
} catch (NoClassDefFoundError | ClassNotFoundException notInstalled) {
    c = DriverManager.getConnection("jdbc:mysql://host:3306/db?useSSL=false", props);
}

MinecraftMysqlJdbc wraps a child-first URLClassLoader pointing at this jar, parented to the platform classloader so com.mysql.cj.* must come from this jar (not the bundled chain). The returned Connection is a standard java.sql.Connection — keep your casts to java.sql.* interfaces; the impl class lives in the child-first classloader and won't down-cast across the boundary.

API surface (all static):

| Method | Returns | |---|---| | connect(String url) | open Connection through this driver | | connect(String url, Properties props) | as above with props | | driver() | the java.sql.Driver instance | | driverVersion() | connector-j version (e.g. "9.1") | | eagerInit() | warm the classloader at plugin enable | | shutdown() | release file handles on plugin disable |

Grim Anti-Cheat's MySQL backend uses this API automatically when this holder is installed.

License

GPL-2.0 with the Universal FOSS Exception 1.0. The exception makes the driver compatible with any FOSS-licensed Minecraft plugin or mod (it's the same license Oracle ships with the Connector/J binary). Modrinth's license tag shows GPL-2.0-only because the SPDX list doesn't have a single identifier for the GPL-2 + FOSS Exception combo — full text in LICENSE.

Issues, source: GitHub.