It's going to /api/1.0/targets instead of /toastergui/targets To reproduce, create a new project, and in the notification at the top of the screen click on the "select targets" link.
fb7160e4228d49a765006d9ba0b810be9f083989 (Bitbake rev: cbf3d652dcbfc1db527eb13cd796fa57d8ff3748)
Verified on master: 5c76cebc24675edb3dff473fce9b67cedff615db