Hello!
I am currently in act V nightmare and cannot proceed. After killing the ancients during the quest “Rite of Passage”. The quest changes to “This quest cannot be completed in this game”. I am playing online solo games. I have not joined any multiplayer game in which this quest could have been completed. I tried restarting and completing the quest again but the same happens.
Help! 
Thanks a lot!
I have the same issue. So i cant continue playing(
Pls Help
Just double checking, you do meet the min level required for the quest correct (its i believe 20 in normal, 40 in nightmare and 60 in hell)
Same for me, i played online in a lobby party, the others have broken the sigil to pass for Mephisto without me, so i cannot go on in the quest. What can I do now?
It’s clvl 20 for Normal. The others you listed are correct.
Source: The Arreat Summit, Quests, Act V, Rite of Passage – Notes:
http://classic.battle.net/diablo2exp/quests/act5.shtml