Unable to create MARS session

Unity Engine
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1

Hi I faced this error when I add MARS Session and MARS Proxy Rule.
Please help to solve this error.

NullReferenceException: Object reference not set to an instance of an object
Unity.MARS.MARSSession.SessionConfigured (Unity.MARS.MARSSession session) (at Library/PackageCache/com.unity.mars@1.2.0/Runtime/Scripts/MARSSession.cs:300)
Unity.MARS.MARSSession.EnsureRuntimeState (UnityEngine.Transform overrideUserRef) (at Library/PackageCache/com.unity.mars@1.2.0/Runtime/Scripts/MARSSession.cs:185)
Unity.MARS.CreateMenuItems.CreateRulesetObject (UnityEditor.MenuCommand command) (at Library/PackageCache/com.unity.mars@1.2.0/Editor/Scripts/Extensions/CreateMenuItems.cs:177)
UnityEditor.GenericMenu:CatchMenu(Object, String[], Int32) (at /Users/builduser/buildslave/unity/build/Editor/Mono/GUI/GenericMenu.cs:119)
2

I was able to solved this by myself.
I found MARS Session component was present without MARS Camera component. So I removed old MARS Session completely then added successfully.
Thanks.