Hi, @ssvpdeveloper, and thank you for your question!
From the nature of the error and the successful login log you received, I would say the error has nothing to do with how you set up authentication with Auth0, and sadly it falls out of the scope of the support I can provide.
What I would do in your situation is check how the Blazor server is configured, adding logs and carefully debugging through the login process.
I wish you a great day!
Sincerely,
Teodor.