Make sure you have the Legacy Toil and Trouble Milestone : Complete Way of the Witch

i pasted this on other posts; i'll paste it here too as it contains the only surefire way i know of to get it to open. once you get your quest (via hopping in someone else's portal, if applicable) try running spire, running altars, and hope your quest will progress enough to get the portal open. make sure you let the game take you out of the end of spire by itself instead of leaving early. if none of that works, the only other way that i know of to fix it is to join someone that is on the first mission (the one that sends you right into spire afterward automatically), and [u]stay until the end[/u] where it will send you into spire. complete that, and the portal will be available to open. the issue is caused by leaving at the end of the mission without letting it take you into spire automatically. you have to wait to get it to progress properly