Unity集成Google Mobile Ads遇System.MissingMethodException求助

这个问题我帮不少开发者排查过，核心原因是Google的Unity Jar Resolver插件在尝试调用Unity版本控制API时失败——要么你的Unity版本里这个API的签名已经变了，要么你压根没启用Unity的版本控制功能。结合你提供的报错日志，给你几个靠谱的解决步骤：

方案1：启用Unity版本控制功能 #

这是最常见的解决方法，因为插件需要修改项目设置文件，需要版本控制的Checkout权限：

• 打开Unity编辑器，顶部菜单选择 Edit > Project Settings > Version Control
• 把Mode选项从Disabled切换成Visible Meta Files（如果用Git的话选这个就行）或者你正在使用的版本控制模式
• 重启Unity，然后重新执行Play Service Resolver的自动解析操作

方案2：升级Google Mobile Ads插件到兼容版本 #

你当前使用的v3.18.2版本比较老旧，可能和你用的新Unity版本（比如2020及以上）的API不兼容：

• 先在Unity的Package Manager里移除旧的Google Mobile Ads插件
• 安装最新稳定版的Google Mobile Ads插件（推荐v4.x及以上版本，已经适配了新Unity的版本控制API）
• 重新配置Android设备设置后再运行解析

方案3：手动修改插件代码（应急临时方案） #

如果暂时没法升级插件，可以临时修改报错的插件代码来适配Unity版本：

• 找到报错文件：Assets/Google/VersionHandlerImpl/ProjectSettings.cs
• 定位到第119行调用Checkout的代码，把原来的单个string参数改成数组形式：

  // 原来的代码
  UnityEditor.VersionControl.Task task = UnityEditor.VersionControl.Provider.Checkout(path, UnityEditor.VersionControl.CheckoutMode.Asset);
  // 修改后的代码（适配Unity 2020+）
  UnityEditor.VersionControl.Task task = UnityEditor.VersionControl.Provider.Checkout(new[] { path }, UnityEditor.VersionControl.CheckoutMode.Asset);
  

• 保存后重新运行解析即可，注意：后续升级插件时这个修改会被覆盖，所以还是优先用前两个方案

你提供的错误日志参考： #

Stopped polling job due to exception: System.MissingMethodException: UnityEditor.VersionControl.Task UnityEditor.VersionControl.Provider.Checkout(string,UnityEditor.VersionControl.CheckoutMode)
at Google.ProjectSettings.Set[T] (System.String name, T value) [0x00024] in /Users/smiles/dev/src/unity-jar-resolver/source/VersionHandlerImpl/src/ProjectSettings.cs:119
at Google.ProjectSettings+c__AnonStorey2.<>m__5 () [0x00000] in /Users/smiles/dev/src/unity-jar-resolver/source/VersionHandlerImpl/src/ProjectSettings.cs:154
at Google.ProjectSettings.SavePreferences (Google.ProjectSettings+SettingsSave saveLevel, System.Action saveToProject, System.Action saveToEditor) [0x00035] in /Users/smiles/dev/src/unity-jar-resolver/source/VersionHandlerImpl/src/ProjectSettings.cs:135
at Google.ProjectSettings.SetBool (System.String name, System.Boolean value) [0x00014] in /Users/smiles/dev/src/unity-jar-resolver/source/VersionHandlerImpl/src/ProjectSettings.cs:153
at GooglePlayServices.SettingsDialog.set_UseJetifier (System.Boolean value) [0x00000] in /Users/smiles/dev/src/unity-jar-resolver/source/PlayServicesResolver/src/SettingsDialog.cs:225
at GooglePlayServices.PlayServicesResolver.CanEnableJetifierOrPromptUser (System.String titlePrefix) [0x00179] in /Users/smiles/dev/src/unity-jar-resolver/source/PlayServicesResolver/src/PlayServicesResolver.cs:2270
at GooglePlayServices.PlayServicesResolver.ResolveUnsafe (System.Action`1[T] resolutionComplete, System.Boolean forceResolution, System.Boolean isAutoResolveJob, System.Boolean closeWindowOnCompletion) [0x00012] in /Users/smiles/dev/src/unity-jar-resolver/source/PlayServicesResolver/src/PlayServicesResolver.cs:1610
at GooglePlayServices.PlayServicesResolver+<ScheduleResolve>c__AnonStorey1E.<>m__40 () [0x00000] in /Users/smiles/dev/src/unity-jar-resolver/source/PlayServicesResolver/src/PlayServicesResolver.cs:1579
at GooglePlayServices.PlayServicesResolver.ExecuteNextResolveJob () [0x00069] in /Users/smiles/dev/src/unity-jar-resolver/source/PlayServicesResolver/src/PlayServicesResolver.cs:1438
at GooglePlayServices.PlayServicesResolver.ScheduleResolve (System.Boolean forceResolution, System.Boolean closeWindowOnCompletion, System.Action`1[T] resolutionCompleteWithResult, System.Boolean isAutoResolveJob) [0x000a7] in /Users/smiles/dev/src/unity-jar-resolver/source/PlayServicesResolver/src/PlayServicesResolver.cs:1592
at GooglePlayServices.PlayServicesResolver.AutoResolve (System.Action resolutionComplete) [0x00017] in /Users/smiles/dev/src/unity-jar-resolver/source/PlayServicesResolver/src/PlayServicesResolver.cs:1113
at GooglePlayServices.PlayServicesResolver.m__48 () [0x00016] in /Users/smiles/dev/src/unity-jar-resolver/source/PlayServicesResolver/src/PlayServicesResolver.cs:1092
at Google.RunOnMainThread.ExecutePollingJobs () [0x0004a] in /Users/smiles/dev/src/unity-jar-resolver/source/VersionHandlerImpl/src/RunOnMainThread.cs:300
UnityEngine.Debug:LogError(Object)
Google.RunOnMainThread:ExecutePollingJobs() (at /Users/smiles/dev/src/unity-jar-resolver/source/VersionHandlerImpl/src/RunOnMainThread.cs:303)
Google.RunOnMainThread:m__17() (at /Users/smiles/dev/src/unity-jar-resolver/source/VersionHandlerImpl/src/RunOnMainThread.cs:414)
Google.RunOnMainThread:RunAction(Action) (at /Users/smiles/dev/src/unity-jar-resolver/source/VersionHandlerImpl/src/RunOnMainThread.cs:234)
Google.RunOnMainThread:ExecuteAll() (at /Users/smiles/dev/src/unity-jar-resolver/source/VersionHandlerImpl/src/RunOnMainThread.cs:406)
UnityEditor.EditorApplication:Internal_CallUpdateFunctions()

内容的提问来源于stack exchange，提问作者Christopher Stupák