Unity Addressables场景下载中已下载场景出现粉色精灵问题求助

我有多个可通过Addressables下载的场景，场景下载完成后加载正常，但只要有任意场景处于下载进程中，其他已下载的场景就会出现粉色精灵（Shader丢失的典型表现）。该问题仅出现在Android构建版本中。

注：释放AsyncOperationHandle时会触发问题，但不释放该Handle则无法将场景加载到内存中。我推测可能和Addressables未加载内置Shader有关，但没找到解决办法。

public class AddreasableSceneThumbnail : MonoBehaviour
{
    [SerializeField] string sceneAddress;
    [SerializeField] Transform downloadProgressUI;
    bool isDownloadStarted;
    bool isDownloaded;
    IEnumerator downloadCour;

    private void Start()
    {
        StartCoroutine(CheckDownload());
    }
    private void OnDestroy()
    {
        if(downloadCour != null)
            StopCoroutine(downloadCour);
        if (downloadHandlerCheck.IsValid())
        {
            Addressables.Release(downloadHandlerCheck);
        }
        if (downloadHandlerDownload.IsValid())
        {
            Addressables.Release(downloadHandlerDownload); 
        }
    }
    AsyncOperationHandle<long> downloadHandlerCheck;
    IEnumerator CheckDownload()
    {
        downloadHandlerCheck = Addressables.GetDownloadSizeAsync(sceneAddress);

        while (!downloadHandlerCheck.IsDone && downloadHandlerCheck.Status !=AsyncOperationStatus.Failed)
        {
            yield return null;
        }

        if (downloadHandlerCheck.Result == 0)
        {
            ActivateButton();
            isDownloaded = true;
        }
        Addressables.Release(downloadHandlerCheck);
    }
    public void OnThumbNailClicked()
    {
        if(isDownloaded)
            Addressables.LoadSceneAsync(sceneAddress,LoadSceneMode.Single);
        if (isDownloadStarted) return;
        isDownloadStarted = true;
        downloadCour= DownloadScene();
        StartCoroutine(downloadCour);
    }
    AsyncOperationHandle downloadHandlerDownload;
    IEnumerator DownloadScene()
    {
        downloadProgressUI.transform.localScale = Vector3.one;
        downloadProgressUI.gameObject.SetActive(true);

        downloadHandlerDownload = Addressables.DownloadDependenciesAsync(sceneAddress);
        while (!downloadHandlerDownload.IsDone)
        {
            downloadProgressUI.localScale = new Vector3(1, 1 - downloadHandlerDownload.PercentComplete, 1);
            yield return null;
        }
        isDownloaded = true;
        ActivateButton();
        Addressables.Release(downloadHandlerDownload); // this is culprit

    }
    public void ActivateButton()
    {
        downloadProgressUI.gameObject.SetActive(false);
    }
}

针对Android平台的这个问题，可尝试以下几种修复思路：

1. 预加载内置核心Shader #

粉色精灵本质是Shader丢失，Android平台下Addressables下载过程中可能意外释放了共享的内置Shader资源。可以将常用的内置Shader（如Standard、UI/Default等）打包进主包，或者通过Addressables标记为Local资源提前加载：

• 在Project窗口找到内置Shader（路径：Assets/Resources/UnityShaders或通过Package Manager查看）
• 将这些Shader添加到Addressables组，设置Load Type为Preload，Location为Local
• 在游戏启动时调用Addressables.LoadAssetsAsync<Shader>(new List<string>{"Shader地址1", "Shader地址2"}, null)预加载，加载完成后无需释放（因为是本地预加载资源）

2. 延迟释放下载Handle #

问题出在释放downloadHandlerDownload时，可改为在场景加载完成后再释放该Handle，避免提前释放导致依赖资源被回收：

IEnumerator DownloadScene()
{
    downloadProgressUI.transform.localScale = Vector3.one;
    downloadProgressUI.gameObject.SetActive(true);

    downloadHandlerDownload = Addressables.DownloadDependenciesAsync(sceneAddress);
    while (!downloadHandlerDownload.IsDone)
    {
        downloadProgressUI.localScale = new Vector3(1, 1 - downloadHandlerDownload.PercentComplete, 1);
        yield return null;
    }
    isDownloaded = true;
    ActivateButton();
    // 暂时不释放，等场景加载完成后再处理
}

// 修改OnThumbNailClicked中的场景加载逻辑
public void OnThumbNailClicked()
{
    if(isDownloaded)
    {
        var loadHandle = Addressables.LoadSceneAsync(sceneAddress, LoadSceneMode.Single);
        StartCoroutine(WaitForLoadAndRelease(loadHandle));
    }
    if (isDownloadStarted) return;
    isDownloadStarted = true;
    downloadCour= DownloadScene();
    StartCoroutine(downloadCour);
}

IEnumerator WaitForLoadAndRelease(AsyncOperationHandle<SceneInstance> loadHandle)
{
    yield return loadHandle;
    if (loadHandle.Status == AsyncOperationStatus.Succeeded)
    {
        // 场景加载完成后再释放下载Handle
        if (downloadHandlerDownload.IsValid())
        {
            Addressables.Release(downloadHandlerDownload);
            downloadHandlerDownload = default;
        }
    }
}

3. 调整资源自动回收设置 #

在Addressables设置中（Window > Asset Management > Addressables > Groups），找到Advanced Settings，将Resource Manager Settings里的Auto Release相关选项暂时关闭，或者调整回收延迟时间，避免在下载过程中误回收已加载的共享资源。

4. 检查场景依赖的Shader打包情况 #

确保所有场景中使用的Shader都被正确包含在Addressables的依赖项中：

• 选中目标场景，在Addressables组中查看其依赖项，确认Shader都被正确标记
• 如果有Shader未被自动添加，手动将其加入对应Addressables组，避免下载时遗漏

内容的提问来源于stack exchange，提问作者Ravi Thapa