A: First possibility: You already created an Edumaps account in the past, either by registering directly or by booking a course with your email address. An account with your email address therefore already exists and the single sign-on does not work.

B: Second possibility: The single sign-on was used in the past and a user account was created with the transmitted email. Our server checks whether the transmitted identifier is already in use and which email is assigned to it. If the identifier was changed but the same email is still transmitted, the single sign-on does not work.