This button leads to /ill/ill-requests.pl?method=generic_confirm&illrequest_id=1 If there are no partners defined this link should not be displayed and the page not accessible (with friendly message what's happening).
This button only shows if the request's backend has the GENREQ status configured in the status_graph, on the current request's status "next_actions" array. Additionally, currently if there are partners but none of the partners have an e-mail address, the drop-down selection for partners shows empty, i.e. the page is accessible but not functional. This should also be taken into account.