I got an error in the console, what is it and how to fix it?

Question

Unity

NullReferenceException: Object reference not set to an instance of an object
UnityEditor.Graphs.Edge.WakeUp () (at <b82d8d0a349d4d70807c2fc5746a710f>:0)
UnityEditor.Graphs.Graph.DoWakeUpEdges (System.Collections.Generic.List`1[T] inEdges, System.Collections.Generic.List`1[T] ok, System.Collections.Generic.List`1[T] error, System.Boolean inEdgesUsedToBeValid) (at <b82d8d0a349d4d70807c2fc5746a710f>:0)
UnityEditor.Graphs.Graph.WakeUpEdges (System.Boolean clearSlotEdges) (at <b82d8d0a349d4d70807c2fc5746a710f>:0)
UnityEditor.Graphs.Graph.WakeUp (System.Boolean force) (at <b82d8d0a349d4d70807c2fc5746a710f>:0)
UnityEditor.Graphs.Graph.WakeUp () (at <b82d8d0a349d4d70807c2fc5746a710f>:0)
UnityEditor.Graphs.Graph.OnEnable () (at <b82d8d0a349d4d70807c2fc5746a710f>:0)

Answer 1

The problem was solved after restarting unity