Deleting the Corrupted flag did allow me to load it. After sleeping it did drop the error again:
System.NullReferenceException: Object reference not set to an instance of an object.
at TypeSerializationUtility.SerializeWithType (ISerializable serializable, System.IO.BinaryWriter binaryWriter) [0x00000] in <00000000000000000000000000000000>:0
at RoutineArgument_SeekPlayerAndTalk.Serialize (System.IO.BinaryWriter binaryWriter) [0x00000] in <00000000000000000000000000000000>:0
at TypeSerializationUtility.SerializeListWithType[T] (System.Collections.Generic.List`1[T] list, System.IO.BinaryWriter binaryWriter) [0x00000] in <00000000000000000000000000000000>:0
at NPCRoutine.Serialize (System.IO.BinaryWriter binaryWriter) [0x00000] in <00000000000000000000000000000000>:0
at WalkUpManager.Serialize (System.IO.BinaryWriter binaryWriter) [0x00000] in <00000000000000000000000000000000>:0
at SerializationManager.SerializePersistent () [0x00000] in <00000000000000000000000000000000>:0
at SerializationManager.Save (System.String saveFileName) [0x00000] in <00000000000000000000000000000000>:0
at SaveUI.Save (System.Int32 saveSlot) [0x00000] in <00000000000000000000000000000000>:0
at UnityEngine.Events.UnityEvent.Invoke () [0x00000] in <00000000000000000000000000000000>:0
at UnityEngine.EventSystems.ExecuteEvents.Execute[T] (UnityEngine.GameObject target, UnityEngine.EventSystems.BaseEventData eventData, UnityEngine.EventSystems.ExecuteEvents+EventFunction`1[T1] functor) [0x00000] in <00000000000000000000000000000000>:0
at UnityEngine.EventSystems.StandaloneInputModule.ReleaseMouse (UnityEngine.EventSystems.PointerEventData pointerEvent, UnityEngine.GameObject currentOverGo) [0x00000] in <00000000000000000000000000000000>:0
at UnityEngine.EventSystems.StandaloneInputModule.ProcessMousePress (UnityEngine.EventSystems.PointerInputModule+MouseButtonEventData data) [0x00000] in <00000000000000000000000000000000>:0
at UnityEngine.EventSystems.StandaloneInputModule.ProcessMouseEvent (System.Int32 id) [0x00000] in <00000000000000000000000000000000>:0
at UnityEngine.EventSystems.StandaloneInputModule.Process () [0x00000] in <00000000000000000000000000000000>:0
at UnityEngine.EventSystems.EventSystem.Update () [0x00000] in <00000000000000000000000000000000>:0
After waiting 24 ingame hours it did fiy itself. Thank you!