Implementing Semantic Versioning for Game Builds

In this lesson, you will learn how to implement semantic versioning to maintain compatibility between your client builds and backend services in a live multiplayer environment.

The Semantic Versioning Standard

As your multiplayer project matures, you will inevitably face "version skew"—the scenario where a client running an older version of your game tries to connect to a server or lobby service expecting a newer data structure. To solve this, we adopt the MAJOR.MINOR.PATCH standard:

• MAJOR: Incremented for breaking changes (e.g., changing the network serialization schema).
• MINOR: Incremented for features that remain backward-compatible (e.g., adding a new lobby metadata property).
• PATCH: Incremented for backward-compatible bug fixes.

Integrating Versioning in Unity

Instead of hardcoding strings, store your version in a ScriptableObject or a static configuration file that the build pipeline can inject. Your lobby system or matchmaking ticket requests should include this version string as a requirement.

public static class GameVersion
{
    // Increment these to prevent incompatible client-server handshakes
    public const int Major = 1;
    public const int Minor = 4;
    public const int Patch = 2;

    public static string GetVersionString() => $"{Major}.{Minor}.{Patch}";
}

Enforcing Compatibility

When a client joins a lobby or connects to a dedicated server, you must perform a "Handshake Validation." If your server-side backend or your Relay session metadata detects a mismatch in the MAJOR version, the connection should be rejected immediately.

public void OnClientConnected(string clientVersion)
{
    if (clientVersion != GameVersion.GetVersionString())
    {
        Debug.LogError("Version Mismatch! Disconnecting client.");
        // Logic to prompt user to update via an external store
        NetworkManager.Singleton.Shutdown();
    }
}

By embedding this versioning logic, you prevent the subtle, hard-to-debug crashes that occur when serialized RPC parameters no longer align with your server's current state. This ensures that your matchmaking system only groups players running identical (or compatible) logic, maintaining the integrity of your network sessions.

Key Takeaway: Implement Semantic Versioning to enforce build compatibility during the handshake process, preventing crashes caused by serialized data mismatches between client and server.