Hello! We have a problem periodically when, at night, my son wants to …

Hello! We have a problem periodically when, at night, my son wants to go to the bathroom and starts screaming in the middle of the night, terribly in a tantrum. I understand that he wants to go to the bathroom, but he flatly refuses to, and won't sit on the potty. I end up having to take him to the bathroom, turn on the water, then he pees and the tantrum stops. During the day, he calmly uses the potty, and he categorically refuses to wear diapers at night. What can be done?