Why does a NullReferenceException appear, although the link is present?

2021.04.28 21:45:57.457 5204 5225 Error Unity NullReferenceException: Object reference not set to an instance of an object

2021.04.28 21:45:57.457 5204 5225 Error Unity at EventManager.UpdateEventInfo (System.UInt32 eventId) [0x00000] in <0f5c51a7befb438a85e5ed2da1233784>:0

2021.04.28 21:45:57.457 5204 5225 Error Unity at EventManager.StartEvent (System.UInt32 eventId) [0x00000] in <0f5c51a7befb438a85e5ed2da1233784>:0

2021.04.28 21:45:57.457 5204 5225 Error Unity at EventManager.BeginRegularEvent (UnityEngine.GameObject obj) [0x0001f] in <0f5c51a7befb438a85e5ed2da1233784>:0

2021.04.28 21:45:57.457 5204 5225 Error Unity at UnityEngine.Events.InvokableCall`1[T1].Invoke (T1 args0) [0x00010] in <92ee4185062b4e4faf57819494c1d4e0>:0

2021.04.28 21:45:57.457 5204 5225 Error Unity at UnityEngine.Events.CachedInvokableCall`1[T].Invoke (System.Object[] args) [0x00001] in <92ee4185062b4e4faf57819494c1d4e0>:0

2021.04.28 21:45:57.457 5204 5225 Error Unity at UnityEngine.Events.UnityEvent.Invoke () [0x00074] in <92ee4185062b4e4faf57819494c1d4e0>:0

2021.04.28 21:45:57.457 5204 5225 Error Unity at UnityEngine.UI.Button.Press () [0x0001c] in :0

2021.04.28 21:45:57.457 5204 5225 Error Unity at UnityEngine.UI.Button.OnPointerClick (UnityEngine.EventSystems.PointerEventData eventData) [0x00009] in :0

2021.04.28 21:45:57.457 5204 5225 Error Unity at UnityEngine.EventSystems.ExecuteEvents.