Unity3D 2017.3无法构建任何项目报错求助

你遇到的是Unity跨小版本升级时典型的UI模块引用路径错乱问题——报错明确指出UnityEngine.UI.dll引用了UnityEngine程序集，但要么找不到该程序集，要么它不允许被包含，大概率是升级后Editor路径残留了旧版本/错误版本的UI扩展文件导致的。

下面是几个经过验证的解决方案，建议按优先级尝试：

1. 清理Unity Editor的UI扩展缓存 #

• 定位报错里提到的UI.dll路径：D:/Program Files/Unity2018/Editor/Data/UnityExtensions/Unity/GUISystem/Standalone/UnityEngine.UI.dll
• 先关闭Unity编辑器，然后删除整个GUISystem文件夹
• 重新打开Unity，它会自动重新生成适配当前2017.3版本的UI扩展文件

2. 重置项目的程序集引用 #

• 在项目的Assets文件夹下创建临时Editor文件夹，新建一个C#脚本，输入以下代码：

using UnityEditor;
using UnityEngine;

public class ResetAssemblyReferences : EditorWindow
{
    [MenuItem("Tools/Reset Assembly References")]
    public static void ShowWindow()
    {
        EditorUtility.DisplayDialog("提示", "即将重置程序集引用，Unity会自动重启", "确认");
        AssetDatabase.Refresh();
        EditorApplication.Exit(0);
    }
}

• 点击顶部菜单栏的Tools > Reset Assembly References，确认后Unity会重启，重启后尝试重新构建

3. 彻底重新安装Unity 2017.3 #

如果前两种方法都无效，说明可能是安装过程中出现了文件损坏：

• 先通过Unity Hub（或官方卸载工具）彻底卸载2017.3版本，注意勾选删除相关缓存文件
• 重新下载2017.3的官方安装包，选择自定义安装，确保勾选GUISystem扩展模块
• 安装完成后创建新的空项目，再尝试构建

补充说明 #

这个问题在Unity 2017系列的小版本升级中比较常见，核心原因是旧版本的扩展文件没有被完全覆盖，导致程序集引用链断裂。另外要注意，你的报错里提到的路径是Unity2018的文件夹，这可能是你之前安装过2018版本，Unity在升级时错误地引用了旧版本的UI文件——所以第一步清理路径时一定要确认是对应2017.3版本的Editor文件夹，不要搞错了！

附原始报错信息：

• ArgumentException: The Assembly UnityEngine is referenced by UnityEngine.UI ('D:/Program Files/Unity2018/Editor/Data/UnityExtensions/Unity/GUISystem/Standalone/UnityEngine.UI.dll'). But the dll is not allowed to be included or could not be found.
  UnityEditor.AssemblyHelper.AddReferencedAssembliesRecurse (System.String assemblyPath, System.Collections.Generic.List1 alreadyFoundAssemblies, System.String[] allAssemblyPaths, System.String[] foldersToSearch, System.Collections.Generic.Dictionary2 cache, BuildTarget target) (at C:/buildslave/unity/build/Editor/Mono/AssemblyHelper.cs:156)
  UnityEditor.AssemblyHelper.FindAssembliesReferencedBy (System.String[] paths, System.String[] foldersToSearch, BuildTarget target) (at C:/buildslave/unity/build/Editor/Mono/AssemblyHelper.cs:196)
  UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)
• Build completed with a result of 'Failed'
  UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)
• UnityEditor.BuildPlayerWindow+BuildMethodException: 3 errors
  at UnityEditor.BuildPlayerWindow+DefaultBuildMethods.BuildPlayer (BuildPlayerOptions options) [0x0020e] in C:\buildslave\unity\build\Editor\Mono\BuildPlayerWindowBuildMethods.cs:181
  at UnityEditor.BuildPlayerWindow.CallBuildMethods (Boolean askForBuildLocation, BuildOptions defaultBuildOptions) [0x00065] in C:\buildslave\unity\build\Editor\Mono\BuildPlayerWindowBuildMethods.cs:88
  UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)

内容的提问来源于stack exchange，提问作者KiritoPlan