# 35114: Scheduling does not support this timestamp

Log Type: APPLICATION

Log Level: ERROR

## Description

This error occurs when the `SendAt` value for a scheduled message is outside the supported scheduling window or is not accepted as a valid timestamp. Use an ISO 8601 UTC timestamp, and make sure Twilio receives the request between 15 minutes and 35 days before the scheduled send time.

### Possible causes

* The `SendAt` value is less than 15 minutes in the future when Twilio receives the request.
* The `SendAt` value is more than 35 days in the future.
* The `SendAt` value is not formatted as a valid ISO 8601 UTC timestamp such as `2026-05-15T14:30:00Z`.
* Your application calculates `SendAt` too close to the minimum scheduling window, and the request reaches Twilio after that minimum has passed.
* Your application converts the scheduled time incorrectly because of a time zone or UTC formatting issue.

### Possible solutions

* Format `SendAt` as an ISO 8601 timestamp in UTC using the pattern `YYYY-MM-DDTHH:MM:SSZ`.
* Update the scheduled time so Twilio receives the request at least 15 minutes before `SendAt`.
* Update the scheduled time so `SendAt` is no more than 35 days in the future.
* Add a buffer beyond the minimum window if you are scheduling close to the earliest supported time.
* Generate and validate the timestamp in UTC before you send the API request.

#### Additional resources

* [Message Scheduling](/docs/messaging/features/message-scheduling)
* [Message resource API reference](/docs/messaging/api/message-resource)
* [Messaging Services](/docs/messaging/services)