I can reproduce this by running:
$ software-center /tmp/google-chrome-beta_current_amd64.deb
and installing/reinstalling it.
It appears that aptdaemon blocks while its investigating the deb and at the
same time s-c is doing
dbus calls to aptdaemon resulting in a blocking UI in s-c
** Also
** Changed in: software-center (Ubuntu)
Status: New = Confirmed
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Title:
software-center crashed with DBusException in
** Changed in: software-center (Ubuntu)
Importance: Undecided = Medium
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Title:
software-center crashed with DBusException in
** Visibility changed to: Public
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https://bugs.launchpad.net/bugs/80
Title:
software-center crashed with DBusException in
_convert_dbus_exception():