Tivoli has opened APAR IC29368 for this.

Basically the client ends with "ANS1074I *** User Abort ***" (scheduler or
cmdline)
or "MSG "ANS5011I Backup Stopped by User" (GUI) instead of displaying the
real error message.

In our case we experienced 3 different errors that produced user aborts:
"ANS1311E Server out of data storage space"
"ANS1448E An error occurred accessing NTFS security information"
(Exchange 2000 Web Store)
"ANS4036E An error occurred saving the registry key"

Instead of displaying the above message, the 4.12 client just ends with the
User Abort.  The 4.11 client displays the proper message.

We experienced this on WIN32 and Solaris 4.12 clients.

Tim Rushforth
City of Winnipeg