Tried building an apk and keeps throwing this error...

ArgumentException: The Assembly UnityEditor is referenced by Assembly-CSharp-firstpass (‘Library/ScriptAssemblies/Assembly-CSharp-firstpass.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:147)
UnityEditor.AssemblyHelper.FindAssembliesReferencedBy (System.String paths, System.String foldersToSearch, BuildTarget target) (at C:/buildslave/unity/build/Editor/Mono/AssemblyHelper.cs:185)
UnityEditor.HostView:OnGUI()

I’m not sure what it means. I have installed android sdk and java jdk. I’m not sure if it matters but i didnt
download android studio. I only downloaded the sdk. Please help.

You seem to be trying to add App42SDK (specifically push notification code) in your unity project.
Their push notification code doesn’t come with their SDK, and it needs to be downloaded/added separately. Just go ahead and grab that from here.

Hey guys thanks! But I figured it out, I apparently was using a 5.5 Android module in unity 5.4! Crazy right!