I was following the tutorial for Member Registration and Login at was at this point https://docs.umbraco.com/umbraco-cms/tutorials/members-registration-and-login#creating-a-new-surfacecontroller where it showed making a custom controller for automatically assigning users a user group when created, I copied the exact code placing it in a

[project name].Controllers

namespace, and I was able to reference it in the

BeginUmbracoForm

on the sign in page, however when I click submit on that form I get a 400 error, it seems it's just not finding that controller, is there something I might be missing that would prevent this from being found.

Usually this indicates that there's something wrong with the antiforgery token, have a read here for hints: https://our.umbraco.com/forum/umbraco-9/107397-status-code-400-on