40159: Conference Instruction does not have a valid 'status_callback_url' parameter

This error occurs when you send a TaskRouter conference instruction with a status_callback_url value that Twilio cannot validate. Conference instructions accept Conference Participants API parameters for the worker leg, and status_callback_url must be a valid HTTP or HTTPS URL string.

• You set status_callback_url to an empty string.
• You passed status_callback_url with the wrong data type instead of a string.
• You provided a malformed URL in status_callback_url.
• The URL is missing the http:// or https:// scheme.
• Your application generated the assignment instruction dynamically and serialized status_callback_url incorrectly.

• Set status_callback_url to a complete, well-formed HTTP or HTTPS URL string.
• Include the full scheme and host in the callback URL, for example https://example.com/conference-events.
• If you build assignment instructions in code, make sure status_callback_url is serialized as a string value.
• If you do not need conference status callbacks, omit status_callback_url instead of sending an empty value.
• Review the Conference Participants API parameters you pass through the TaskRouter conference instruction and correct any invalid callback configuration before retrying the reservation update.

• Task Reservation Resource
• Conferences Participants subresource
• Assigning Tasks to Workers: Handling Assignment Callbacks