Problem statement
Passwordless SMS logins are failing with an error message:
Client authentication is required.
Tenant Log entry example:
Cause
This error will occur if a client_id is omitted from the POST request to https://{{auth0_domain}}/passwordless/start , or if the login is for a Regular Web App and the client_secret is incorrect or omitted and the application does not have the Authentication Method set to None.
Solution
Make sure that the POST request to https://{{auth0_domain}}/passwordless/start is including a client_id.
If the login is to a Regular Web App that is using an Authentication Method other than None , make sure that the client_secret is also included and accurate.
