il2cpp problem

ERROR: Failed to resolve base type System.ServiceModel.Configuration.BehaviorExtensionElement for type ProtoBuf.ServiceModel.ProtoBehaviorExtension Fatal error in Mono CIL Linker System.Exception: ERROR: Failed to resolve base type System.ServiceModel.Configuration.BehaviorExtensionElement for type ProtoBuf.ServiceModel.ProtoBehaviorExtension at UnusedBytecodeStripper2.ResolveFromMonoBehaviours.IsMonoBehaviourOrScriptableObject (Mono.Cecil.TypeDefinition type) [0x00000] in <filename unknown>:0 at System.Linq.Enumerable+<CreateWhereIterator>c__Iterator1E`1[Mono.Cecil.TypeDefinition].MoveNext () [0x00000] in <filename unknown>:0 at UnusedBytecodeStripper2.ResolveFromMonoBehaviours.Process (Mono.Linker.LinkContext context) [0x00000] in <filename unknown>:0 at Mono.Linker.Pipeline.Process (Mono.Linker.LinkContext context) [0x00000] in <filename unknown>:0 at Mono.Linker.Driver.Run () [0x00000] in <filename unknown>:0 at Mono.Linker.Driver.RunDriverWithErrorHandling (Mono.Linker.Driver driver) [0x00000] in <filename unknown>:0 at Mono.Linker.Driver.RunDriver (Mono.Linker.Driver driver) [0x00000] in <filename unknown>:0 stderr: UnityEngine.DebugLogHandler:Internal_Log(LogType, String, Object) UnityEngine.DebugLogHandler:LogFormat(LogType, Object, String, Object[]) UnityEngine.Logger:Log(LogType, Object) UnityEngine.Debug:LogError(Object) UnityEditorInternal.Runner:RunManagedProgram(String, String, String, CompilerOutputParserBase) (at /Users/builduser/buildslave/unity/build/Editor/Mono/BuildPipeline/Il2Cpp/IL2CPPUtils.cs:94) UnityEditorInternal.AssemblyStripper:RunAssemblyLinker(IEnumerable`1, String&, String&, String, String) (at /Users/builduser/buildslave/unity/build/Editor/Mono/BuildPipeline/AssemblyStripper.cs:107) UnityEditorInternal.AssemblyStripper:StripAssembliesTo(String[], String[], String, String, String&, String&, String, IIl2CppPlatformProvider, IEnumerable`1, Boolean) (at /Users/builduser/buildslave/unity/build/Editor/Mono/BuildPipeline/AssemblyStripper.cs:100) UnityEditorInternal.AssemblyStripper:RunAssemblyStripper(String, IEnumerable, String, String[], String[], String, IIl2CppPlatformProvider, RuntimeClassRegistry, Boolean) (at /Users/builduser/buildslave/unity/build/Editor/Mono/BuildPipeline/AssemblyStripper.cs:201) UnityEditorInternal.AssemblyStripper:StripAssemblies(String, IIl2CppPlatformProvider, RuntimeClassRegistry, Boolean) (at /Users/builduser/buildslave/unity/build/Editor/Mono/BuildPipeline/AssemblyStripper.cs:131) UnityEditorInternal.IL2CPPBuilder:Run() (at /Users/builduser/buildslave/unity/build/Editor/Mono/BuildPipeline/Il2Cpp/IL2CPPUtils.cs:201) UnityEditorInternal.IL2CPPUtils:RunIl2Cpp(String, String, IIl2CppPlatformProvider, Action`1, RuntimeClassRegistry, Boolean) (at /Users/builduser/buildslave/unity/build/Editor/Mono/BuildPipeline/Il2Cpp/IL2CPPUtils.cs:128) UnityEditor.iOS.PostProcessiPhonePlayerostProcess(iOSBuildPostprocessor, BuildTarget, String, String, String, String, String, String, String, BuildOptions, RuntimeClassRegistry) (at /Users/builduser/buildslave/unity/build/PlatformDependent/iPhonePlayer/Extensions/Managed/BuildPostProcessor.cs:403) UnityEditor.iOS.iOSBuildPostprocessorostProcess(BuildPostProcessArgs) (at /Users/builduser/buildslave/unity/build/PlatformDependent/iPhonePlayer/Extensions/Managed/ExtensionModule.cs:148) UnityEditor.PostprocessBuildPlayerostprocess(BuildTarget, String, String, String, Int32, Int32, String, String, BuildOptions, RuntimeClassRegistry) (at /Users/builduser/buildslave/unity/build/Editor/Mono/BuildPipeline/PostprocessBuildPlayer.cs:316) UnityEditor.BuildPipeline:BuildPlayerInternalNoCheck(String[], String, BuildTarget, BuildOptions, Boolean, UInt32&) UnityEditor.BuildPipeline:BuildPlayerInternal(String[], String, BuildTarget, BuildOptions, UInt32&) (at /Users/builduser/buildslave/unity/build/artifacts/generated/common/editor/BuildPipelineBindings.gen.cs:212) UnityEditor.BuildPipeline:BuildPlayer(String[], String, BuildTarget, BuildOptions) (at

 

please help me!!