Previously I could found many solutions to common problems at: http://progress.atgnow.com/esprogress/Group.jsp?bgroup=sonic
If have found that the ABL KB is now at: http://progresscustomersupport-survey.force.com/OpenEdgeKB
But that KB doesn't seem to include Sonic related articles.
Support (including knowledge base) should be here: http://progresslink.progress.com/supportlink
But you will need to register for SupportLink before you get access.