Product: Programmable Chat
The requested messaging service SID does not belong to your account.
You may have copied/pasted incorrectly, or your API request targeted a different account (e.g. if you have several Projects or several Twilio accounts).
Double-check the Messaging Service SID, confirming that it belongs to your account. Check whether you are authenticating against Twilio with the same account. With these matching, the request will succeed.