UNetWeaver error after update

Hi, Weird thing : after i updated from 5.4.0f3 to the version 5.5.2f1 i had two problems :

1) I couldn't open MonoDevelop(i don't like Visual Studio) but this was fixed after i found an already answered question here where the suggestion was to re-install the GTK

2)I've got these errors:

 UNetWeaver error: parameter [Light] is of the type [UnityEngine.Light] is not a valid type, please make sure to use a valid type.
 UnityEngine.Debug:LogError(Object)
 Unity.UNetWeaver.Log:Error(String) (at C:/buildslave/unity/build/Extensions/Networking/Weaver/Program.cs:20)
 Unity.UNetWeaver.Weaver:IsValidTypeToGenerate(TypeDefinition) (at C:/buildslave/unity/build/Extensions/Networking/Weaver/UNetWeaver.cs:1563)
 Unity.UNetWeaver.Weaver:GenerateWriterFunction(TypeReference) (at C:/buildslave/unity/build/Extensions/Networking/Weaver/UNetWeaver.cs:563)
 Unity.UNetWeaver.Weaver:GetWriteFunc(TypeReference) (at C:/buildslave/unity/build/Extensions/Networking/Weaver/UNetWeaver.cs:295)
 Unity.UNetWeaver.NetworkBehaviourProcessor:GenerateSerialization() (at C:/buildslave/unity/build/Extensions/Networking/Weaver/UNetBehaviourProcessor.cs:471)
 Unity.UNetWeaver.NetworkBehaviourProcessor:Process() (at C:/buildslave/unity/build/Extensions/Networking/Weaver/UNetBehaviourProcessor.cs:71)
 Unity.UNetWeaver.Weaver:ProcessNetworkBehaviourType(TypeDefinition) (at C:/buildslave/unity/build/Extensions/Networking/Weaver/UNetWeaver.cs:1096)
 Unity.UNetWeaver.Weaver:CheckNetworkBehaviour(TypeDefinition) (at C:/buildslave/unity/build/Extensions/Networking/Weaver/UNetWeaver.cs:1620)
 Unity.UNetWeaver.Weaver:Weave(String, IEnumerable`1, IAssemblyResolver, String, String, String) (at C:/buildslave/unity/build/Extensions/Networking/Weaver/UNetWeaver.cs:1739)
 Unity.UNetWeaver.Weaver:WeaveAssemblies(IEnumerable`1, IEnumerable`1, IAssemblyResolver, String, String, String) (at C:/buildslave/unity/build/Extensions/Networking/Weaver/UNetWeaver.cs:1837)
 Unity.UNetWeaver.Program:Process(String, String, String, String[], String[], IAssemblyResolver, Action`1, Action`1) (at C:/buildslave/unity/build/Extensions/Networking/Weaver/Program.cs:34)
 UnityEditor.Scripting.Serialization.Weaver:WeaveUnetFromEditor(String, String, String, String, Boolean)
 


 UNetWeaver error: GenerateSerialization for energySphereManager unknown type [UnityEngine.Light]. UNet [SyncVar] member variables must be basic types.
 UnityEngine.Debug:LogError(Object)
 Unity.UNetWeaver.Log:Error(String) (at C:/buildslave/unity/build/Extensions/Networking/Weaver/Program.cs:20)
 Unity.UNetWeaver.NetworkBehaviourProcessor:GenerateSerialization() (at C:/buildslave/unity/build/Extensions/Networking/Weaver/UNetBehaviourProcessor.cs:479)
 Unity.UNetWeaver.NetworkBehaviourProcessor:Process() (at C:/buildslave/unity/build/Extensions/Networking/Weaver/UNetBehaviourProcessor.cs:71)
 Unity.UNetWeaver.Weaver:ProcessNetworkBehaviourType(TypeDefinition) (at C:/buildslave/unity/build/Extensions/Networking/Weaver/UNetWeaver.cs:1096)
 Unity.UNetWeaver.Weaver:CheckNetworkBehaviour(TypeDefinition) (at C:/buildslave/unity/build/Extensions/Networking/Weaver/UNetWeaver.cs:1620)
 Unity.UNetWeaver.Weaver:Weave(String, IEnumerable`1, IAssemblyResolver, String, String, String) (at C:/buildslave/unity/build/Extensions/Networking/Weaver/UNetWeaver.cs:1739)
 Unity.UNetWeaver.Weaver:WeaveAssemblies(IEnumerable`1, IEnumerable`1, IAssemblyResolver, String, String, String) (at C:/buildslave/unity/build/Extensions/Networking/Weaver/UNetWeaver.cs:1837)
 Unity.UNetWeaver.Program:Process(String, String, String, String[], String[], IAssemblyResolver, Action`1, Action`1) (at C:/buildslave/unity/build/Extensions/Networking/Weaver/Program.cs:34)
 UnityEditor.Scripting.Serialization.Weaver:WeaveUnetFromEditor(String, String, String, String, Boolean)
 

and

 Failure generating network code.
 UnityEditor.Scripting.Serialization.Weaver:WeaveUnetFromEditor(String, String, String, String, Boolean)

So the thing is that i've had similar to these errors(UNet weaver) sometimes on previous versions (3-5 times) and a simple restart of Unity would fix it but that's not the case here.

Any suggestions? I didn't try to re-install/repair, is there a chance it would fix the problem??

EDIT : I tried to load the backup back in my 5.4.0f3 Unity -i kept the old edition for the same reason i have a backup of my projects- and it works.

The reason i want the new version is because i think there are some bugs on the unet part because i've been having a really hard time to do a simple thing like playerPrefab selection script, every suggestion i found on the internet for such script didn't work for me(but it did work for the guy who was asking) so i left the project alone for about three months but now i'm ready to try again and i'm hoping that the update will help me on that