57008: 'EventType' format must be String

Twilio returns this error when the request includes EventType, but the value is not a string. This code appears in the Messaging error dictionary.

• EventType was sent in a format other than a string.
• The request payload was built or serialized incorrectly, so EventType did not reach Twilio as a string.

• Pass EventType as a string value in the request.
• Review the code that builds the request payload and make sure EventType stays a string before you send it.
• Check the error logs to inspect the exact request that Twilio received.

• Programmable Messaging
• Message resource
• Debugging Your Twilio Application