SPA Passwordless Flow getting "Client authentication is required error"


I’m setting up Passwordless login in my Single Page Application. The application is hosted in my Staging tenant.

My web app is using the auth0-js SDK. When making the passwordlessStart request, I get a 403 error response with the message: “Client authentication is required error”.

I’ve confirmed that the request includes: the correct client_id, a valid redirect_uri, and a valid audience. This flow works in my local environment using the Dev tenant.

Am I missing something? Thanks in advance for your help!


Hey. Thanks for reaching out to community !!

The error might have occurred because of the way app and grant types were setup. Please make sure the required grant types are setup and the application has to be “Single Page Application” since auth0.js is a browser based auth client.

Let me know if the change works well. Thanks and looking forward to your response.


Hello Guatham!

Thank you for your advice. I have confirmed that my application is a “Single Page Application”. The following grant types are enabled: “Implicit”, “Authorization Code”, “Refresh Token”.

These above configuration settings are identical to the settings in my Development application, which I have been able to use successfully.

Please let me know if there’s anything else I can try or if I can include any logs or other information to help you.


Hello Gautham,

I just want to let you know that I have fixed the issue. I toggled the application type to “Regular Web Application” and then BACK to “Single Page Application”. It started working after I toggled it back to “Single Page Application”. I hope this helps anyone else who may encounter this unusual error in the future.


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