Found the cause, the package was trying to add a group but the server
that was being upgraded was configured to use LDAP authentication and
the LDAP server it pointed to was down so libbrlapi repeatedly tried to
run groupadd which couldn't complete successfully. I switched to the
text console with CTRL-ALT-F1 and killed to groupadd process which
allowed the installation to complete.

On 2015-12-26 01:16, alekz wrote:
> Hello,
>
> Trying to upgrade a SLES11SP4 VM running on ESXi 6.0 to SLES12SP1 by
> booting from the ISO and selecting Upgrade.
>
> The upgrade goes well until it comes to Installing
> libbrlapi0_6-5.1-7.29.x86_64.rpm (installed size 123.9 KiB)
>
> At this point the CPU usage goes to 100% and nothing else happens, it is
> just stuck, I've waited for about 20 minutes before reverting to a snapshot.
>
> Any tips on how to proceed?
>
> Thanks
>