SuperTokens is an open source authentication solution offering features like: Different types of login: Email / password, Passwordless (OTP or Magic link based).

SuperTokens.com

when does: response.UnknownRoleError != nil while the adding a role to a user? I've created a particular role but I get this error when attempting to attach it to a user.

this happens if you have not created the role in supertokens first

See this: https://supertokens.com/docs/userroles/creating-role

That's weird because I've created the other roles in the same segment of code and not had an issue...

hmm. You can query the core to check all the roles that exist: https://app.swaggerhub.com/apis/supertokens/CDI/2.16.2#/User%20Roles%20Recipe/getRoles

Did a SQL query on the postgres container and found that the role was created before (roles table).

Hmm. Then is is possible that you have mistyped the role when associating it with the user?