I\'m using the XCode 4.2 beta (build 4D199) on Lion, and can\'t access the Developer Documentation in XCode 4.2 anymore. When I attempt to log-in, I get a pop-up telling me the
The situation was fixed for me by Apple / XCode itself, as it automatically downloaded the (newly available?) "iOS 5.0 Library" documentation files. Documentation now runs from a complete local copy.
To be sure you get this too you need to have the automatic download of documentation files turned on.
Preferences > Downloads > Documentation > Check for and install updates automatically
(You can also download the files manually by clicking on "Check and install now")