I too Had This Error....displaying on SCM 5.0 'Live cache lock handler not available'.
Asked to my Basis Guy. He then Hit
Tcode : LC10. --->Live Cache Monitor Page--->Choose DB Connection: LCA or your 'Company's DBCONN' name---> then At Left side Choose Administration Folder--->Click on Configuring.
It Asks for Starting of Live-Cache Server ----Just Choose START.
Wait for it to Start and That's all......Enjoy SCM APO.
It worked for me.....
