When using RegisterMapEvent to register a dungeon, an error occurs: Error while decoding instance data: Data is not valid base-64

RegisterMapEvent(600, 4, function(event, instance_data, map, diff) end)

local event1 = function(event, instance_data, map, diff) end;RegisterMapEvent(600, 4, event1)

All types of events cause this error.

Symptom
All boss scripts in the registered dungeon become non-functional. Bosses can only perform normal auto-attacks (no special skills or abilities).