registering as a new user ends up with error

[kukoman]

An unhandled exception occurred while processing the request.
ArgumentNullException: Value cannot be null. (Parameter 'items')
Microsoft.AspNetCore.Mvc.Rendering.MultiSelectList..ctor(IEnumerable items, string dataValueField, string dataTextField, IEnumerable selectedValues, string dataGroupField)

[deanitz]

Most probably you are trying to use too short password, or another invalid parameter in register form.
Sadly this is not handled correctly in course code.
I would suggest you to debug Mango.Services.Identity AccountController.Register method
Indeed I understand that this post is more than 6 months old