Can't update schedule with API

I was just trying to disassociate team and schedule with API call. But I got error like.
“error”: {
“message”: “Invalid Schedule”,
“code”: 3001,
“errors”: {
“rotation_layers.members.base”: [
“Stakeholders cannot be added to schedules”

Previously, I was able to do it without any problems. So, what’s wrong with this error? What’s wrong with my schedule?

One or more of the target user accounts you are attempting to add are stakeholder accounts and not at least responder level. They cannot be added because they cannot be part of response request action.