Unity2019でビルドの際にエラーが発生する

Unityおよびプログラミング初心者です。WindowsのUnity2018で開発したプロジェクトを、MacのUnity2019に移して開発しようとしたのですが、ビルドの際にエラーが発生します。3日間作業が止まってしまっています。

エラー内容

ArgumentNullException: Value cannot be null.
Parameter name: path1
System.IO.Path.Combine (System.String path1, System.String path2) (at <437ba245d8404784b9fbab9b439ac908>:0)
UnityEditor.Utils.Paths.Combine (System.String[] components) (at /Users/builduser/buildslave/unity/build/Editor/Mono/Utils/Paths.cs:29)
UnityEditor.Android.AndroidGradleRoot.GetGradleLaunchJarPath (System.String directory) (at <8656af08553f4582a8969c722a26e39b>:0)
UnityEditor.Android.GradleWrapper.GetBaseCommand (System.Int32 jvmHeapSize) (at <8656af08553f4582a8969c722a26e39b>:0)
UnityEditor.Android.GradleWrapper.Run (UnityEditor.Android.AndroidJavaTools javaTools, System.String workingdir, System.String task,System.Action`1[T] progress) (at <8656af08553f4582a8969c722a26e39b>:0)
UnityEditor.Android.PostProcessor.Tasks.BuildGradleProject.Execute (UnityEditor.Android.PostProcessor.PostProcessorContext context) (at <8656af08553f4582a8969c722a26e39b>:0)
UnityEditor.Android.PostProcessor.PostProcessRunner.RunAllTasks (UnityEditor.Android.PostProcessor.PostProcessorContext context) (at <8656af08553f4582a8969c722a26e39b>:0)
UnityEditor.Android.PostProcessAndroidPlayer.PostProcess (UnityEditor.BuildTarget target, System.String stagingAreaData, System.String stagingArea, System.String playerPackage, System.String installPath, System.String companyName, System.String productName,UnityEditor.BuildOptions options, UnityEditor.RuntimeClassRegistry usedClassRegistry, UnityEditor.Build.Reporting.BuildReport report) (at <8656af08553f4582a8969c722a26e39b>:0)
UnityEditor.Android.AndroidBuildPostprocessor.PostProcess (UnityEditor.Modules.BuildPostProcessArgs args, UnityEditor.BuildProperties& outProperties) (at <8656af08553f4582a8969c722a26e39b>:0)
UnityEditor.PostprocessBuildPlayer.Postprocess (UnityEditor.BuildTargetGroup targetGroup, UnityEditor.BuildTarget target, System.String installPath, System.String companyName, System.String productName, System.Int32 width, System.Int32 height, UnityEditor.BuildOptions options, UnityEditor.RuntimeClassRegistry usedClassRegistry, UnityEditor.Build.Reporting.BuildReport report) (at /Users/builduser/buildslave/unity/build/Editor/Mono/BuildPipeline/PostprocessBuildPlayer.cs:340)UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr) (at /Users/builduser/buildslave/unity/build/Modules/IMGUI/GUIUtility.cs:187)