Error launching host dialog: 'NoneType' object has no attribute '__getitem__'

_hostinfo is initialized as None

connection.py:__init__:236 self._hostinfo = None

The code that fails has a check on backend is open to be sure it is initialized.
And the init of that value is at
connection.py:_tick:1331 self._hostinfo = self._backend.getInfo()

This polls for new objects regularly.
There might be a race of the backend being opened, but no updates yet completed.
That might be more likely for a more remote connection that is slow, but local ssh sounds fast.

A safety check to not be None might be worth to be added just to be sure.

I submitted a fix upstream for the consideration of the subject matter experts
=> https://github.com/virt-manager/virt-manager/pull/32

MP with the fix added to the packaging available at: https://code.launchpad.net/~paelzer/ubuntu/+source/virt-manager/+git/virt-manager/+merge/356334

But the time to the Final Freeze is close, so it is rather soon or will need to be converted to an SRU later.

I have prepared this to be uploaded, but I have hit an FTBFS in virt-manager that wasn't there last time :-/

I have to analyze and fix it and then cosmic likely is closed for uploads.
So FYI - fixing this will take a bit more time than intended.

Bug for the build issue is bug 1796932

This bug was fixed in the package virt-manager - 1:1.5.1-0ubuntu2

---------------
virt-manager (1:1.5.1-0ubuntu2) cosmic; urgency=medium

  * d/p/lp-1794315-connection-avoid-failing-on-NoneType.patch: fix a race
    (worse on slow remote connections) that would break connecting to a
    remote (LP: #1794315)
  * d/p/lp-1796932-tests-osdict-fix-ordering-issue-with-new-osinfo.patch:
    fix FTBFS due to self-tests failing with new osinfo (LP: #1796932)

 -- Christian Ehrhardt <email address hidden> Tue, 09 Oct 2018 16:57:42 +0200

Added an SRU Template and did a test build in [1]
LGTM, opening up the MP [2] for review towards extra confidence.

[1]: https://launchpad.net/~ci-train-ppa-service/+archive/ubuntu/3478/+packages
[2]: https://code.launchpad.net/~paelzer/ubuntu/+source/virt-manager/+git/virt-manager/+merge/356647

MP approved and made available to the SRU team in Bionic-unapproved.

Hello Marius, or anyone else affected,

Accepted virt-manager into bionic-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/virt-manager/1:1.5.1-0ubuntu1.1 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested and change the tag from verification-needed-bionic to verification-done-bionic. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-bionic. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

As outlined a direct test of the issue is hard to perform.
So I did more a general regression check diving through various options of libvirt pre/post an upgrade to proposed 1:1.5.1-0ubuntu1.1

In addition I ssh connected to a remote host (horsea), but as I said before it didn't trigger the bug (but at least it confrirmed ssh remotes are still working as we touched code there.

Thereby, setting verification done

This bug was fixed in the package virt-manager - 1:1.5.1-0ubuntu1.1

---------------
virt-manager (1:1.5.1-0ubuntu1.1) bionic; urgency=medium

  * d/p/lp-1794315-connection-avoid-failing-on-NoneType.patch: fix a race
    (worse on slow remote connections) that would break connecting to a
    remote (LP: #1794315)

 -- Christian Ehrhardt <email address hidden> Tue, 09 Oct 2018 16:57:42 +0200

The verification of the Stable Release Update for virt-manager has completed successfully and the package has now been released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.