No authenticationScheme was specified, and there was no DefaultChallengeScheme found

In Scheme, if you encounter the error message "No authenticationScheme was specified, and there was no DefaultChallengeScheme found," it means that you have not provided an authentication scheme or a default challenge scheme in your code.

To resolve this issue, you need to specify an authentication scheme or set a default challenge scheme. The authentication scheme defines how the client authenticates itself to the server, while the challenge scheme defines how the server challenges the client for authentication.

You can specify an authentication scheme by using the authenticationScheme parameter when making a request to the server. For example, if you want to use the Basic authentication scheme, you can set the authenticationScheme parameter to 'basic.

If you want to set a default challenge scheme, you can use the setDefaultChallengeScheme procedure. This procedure takes the scheme name as an argument and sets it as the default challenge scheme for the server.

Here's an example of how you can set the default challenge scheme to Basic:

(setDefaultChallengeScheme 'basic)

By specifying an authentication scheme or setting a default challenge scheme, you should be able to resolve the "No authenticationScheme was specified, and there was no DefaultChallengeScheme found" error in Scheme.