Error: Grant type '' not allowed for the client

I have a SPA client setup yesterday, and it worked fine this morning…
Suddenly, I started getting an error: Grant type '' not allowed for the client, when trying to login to the application.
Reviewing the console, I see a 403 error from the URL

Error: Unsuccessful HTTP response at c. ( at c.r.emit ( at XMLHttpRequest.e.onreadystatechange (

I’m using a test environment and plain http, not https. Any idea what can be wrong?

Please see the following post: Error "Grant type 'password' not allowed for the client." for Resource Owner Password flow - Auth0 Community

That worked. Thank you!