20151: Authentication Failed

This error indicates that authentication with the provided JWT failed when Twilio attempted to validate the token for an API/SDK request. It is listed in Twilio's Error and Warning Dictionary as Authentication Failed under API errors. Twilio Access Tokens are JWTs used to authenticate client-side SDKs, and incorrect or invalid tokens will fail authentication.

• Invalid JWT header.
• Invalid iss or sub values in the token.
• Invalid claim set in the token payload.
• Token time-related issues, such as expiration set in the future, expired or invalid expiration, or expiration exceeding the maximum allowed lifetime.

• Re-generate the Access Token on your server using the correct API Key SID and secret, and ensure the token header and payload are properly formed: typ must be JWT, alg must be HS256, and cty must be twilio-fpa;v=1; include required claims like iss (API Key SID), sub (Account SID), iat, and appropriate grants.
• Verify token lifetime settings: set exp within the permitted window (tokens are short‑lived and have a maximum age of 24 hours) and avoid setting nbf in the future relative to the server time. If needed, reissue a fresh token.
• Use the Twilio Console Debugger and error logs to inspect the specific event and any accompanying, more granular token error codes to pinpoint the underlying cause.

• Access Tokens
• Debugging Your Twilio Application