Cause
The campaign dates are not valid: ends_at is not after starts_at, the duration exceeds 365 days, starts_at has already passed when scheduling with schedule, or ends_at has already passed when opening with open.
What to do
Fix the campaign dates.
application/problem+json
{
"type": "https://masnet.com/developers/errors/invalid_dates",
"title": "Invalid dates",
"status": 422,
"detail": "...",
"code": "invalid_dates",
"correlation_id": "..."
}