Steps to replicate:
1) Setup DSpace so it is hosted at / and not at /xmlui
2) Register as a new user
3) Receive email from DSpace
4) Click on link in email
5) Complete the registration in DSpace
6) You are now presented with a link to "Go to DSpace home", inspect this link, the href will be blank
Solution is to add a "/" to the contextPath like in other XMLUI files.