If for whatever reason you need to make a custom updater, here is how. Updaters as the name suggests update the numbers when the versioning system is in use. These are modular so you can add your own easily without needing to edit anything outside of your addition.

🔺 Build Updater

To add one, add a new script into an editor folder and call it whatever you want.

When compiled, implement the IBuildUpdater interface. This contains a single method called OnBuildVersionIncremented() with BuildTarget as a parameter. Along with an int property to define the order it should run in, set this to 0 if you don’t need the updated version number, greater than 0 if you do. You then add your implementation inside of this method to update the build number.

Example below of the android bundle code updater:

public int UpdateOrder => 0;

public void OnBuildVersionIncremented(BuildTarget buildTarget)
{
    if (buildTarget != BuildTarget.Android) return;
    if (BuildVersionsEditorUtil.BuildOptions.androidUpdateBundleCode == AssetUsageType.Disabled) return;
    if (!BuildHandler.Get<AndroidBundleCodeUpdater>().Choice) return;

    PlayerSettings.Android.bundleVersionCode++;
}

🔄 Syncable Updater

To make your update sync with the sync options, implement the ISyncable interface. This contains a single method called OnVersionSync() with a string as a parameter which will be the version number in string form to sync to.

public void OnVersionSync(string version)
{
    for (var i = 0; i < GameAnalytics.SettingsGA.Build.Count; i++)
    {
        GameAnalytics.SettingsGA.Build[i] = version;
    }
}

💬 Pre-Build Dialogue Extension

This allows you to add a dialogue box ahead of the build starting to help control whether the updater will function. If you wish to use this them implement the IPreBuildDialogue interface. This contains a method called OnPreBuildDialogue() with BuildTarget as a parameter. Then implement the relevant logic for the dialogue box, using EditorUtility.DisplayDialog

Unity - Scripting API: EditorUtility.DisplayDialog

You should register the result of this choice with the BuildHandler if you need to use its result. Which you likely will. To do this just call the Register() method on the BuildHandler class and enter a new instance of the HandlerDialogueData struct, passing in the class name as the id & the result as the value.

You can get the class name via typeof(T).Name or via UtilEditor.GetClassName. The id needs to be the class name for the system to work, as you’d only have one result per class that implements the interface for dialogue boxes.

Then to get the result in another method such as the build updater interface method, you use the BuildHandler.Get() method entering the class type in <> brackets and then using the choice from that method to which will be the choice the user made from the dialogue box that build. An example from the android bundle code updater below:

An example from the android bundle code updater:

public void OnPreBuildDialogue(BuildTarget target)
{
    if (target != BuildTarget.Android) return;
    if (BuildVersionsEditorUtil.BuildOptions.androidUpdateBundleCode != AssetUsageType.PromptMe)
    {
        BuildHandler.Register(new HandlerDialogueData(BuildVersionsEditorUtil.GetClassName<AndroidBundleCodeUpdater>(), true));
        return;
    }

    var currentBundleCode = PlayerSettings.Android.bundleVersionCode;

    var choice = EditorUtility.DisplayDialog("Build Versions | Android Bundle Code Updater",
        $"Do you want to increment the bundle code for this build?\\n\\nThis will update the code from {currentBundleCode} to {currentBundleCode + 1}.\\n\\nYou can disable this prompt in the asset settings.",
        $"Yes (Set to {currentBundleCode + 1})", $"No (Leave as {currentBundleCode})");
            
    BuildHandler.Register(new HandlerDialogueData(BuildVersionsEditorUtil.GetClassName<AndroidBundleCodeUpdater>(), choice));
}