35126: The ScheduleType value provided is not supported for this channel

This error occurs when you try to schedule a Programmable Messaging message with a ScheduleType value that the selected channel does not accept. For scheduled messages, Twilio accepts only fixed, and scheduled messaging is supported for SMS, MMS, RCS, and WhatsApp.

• You set ScheduleType to a value other than fixed.
• You tried to schedule a message on a channel that does not support Message Scheduling. Scheduled messaging is supported for SMS, MMS, RCS, and WhatsApp.
• You submitted a scheduling request without MessagingServiceSid. To create a scheduled message, include MessagingServiceSid with ScheduleType and SendAt.

• Set ScheduleType to fixed.
• Send the message through a supported channel if you need scheduling. Use SMS, MMS, RCS, or WhatsApp for scheduled sends.
• Include MessagingServiceSid and a valid SendAt value when you create the message. SendAt must be an ISO-8601 timestamp between 15 minutes and 35 days in the future.
• If you are sending on a channel that does not support scheduling, remove the scheduling parameters and send the message immediately.

• Message Scheduling
• Messages resource
• Get started with Messaging Services