/usr/lib/gvfs/gvfs-udisks2-volume-monitor:11:g_type_check_instance_cast:unmount_operation_is_eject:unmount_data_complete:unmount_cb:g_simple_async_result_complete

That issue should be fixed with 1.24.2 https://git.gnome.org/browse/gvfs/commit/?h=gnome-3-16&id=404f3ea1231551d1784ef419db18510c88cbe798

the bugfix version include the needed change has been uploaded to wily and vivid (waiting for review)

This bug was fixed in the package gvfs - 1.24.2-0ubuntu1

---------------
gvfs (1.24.2-0ubuntu1) wily; urgency=medium

  * New upstream version
    - udisks2: Fix a crash when unmounting (lp: #1500516)
    - udisks2: Handle libsecret errors properly to avoid a crash
      (lp: #1132250)
    - mtp: Copy mtime when pulling (lp: #1175947)
    - gvfs-open: Do not alter uris before use (lp: #1453174)

 -- Sebastien Bacher <email address hidden> Tue, 29 Sep 2015 11:48:31 +0200

Hello errors.ubuntu.com, or anyone else affected,

Accepted gvfs into vivid-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/gvfs/1.24.2-0ubuntu0.1 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 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 to verification-done. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed. In either case, details of your testing will help us make a better decision.

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

the errors.ubuntu.com report has no entry for the new version, seems to work

This bug was fixed in the package gvfs - 1.24.2-0ubuntu0.1

---------------
gvfs (1.24.2-0ubuntu0.1) vivid; urgency=medium

  * New upstream version
    - udisks2: Fix a crash when unmounting (lp: #1500516)
    - mtp: Copy mtime when pulling (lp: #1175947)
    - gvfs-open: Do not alter uris before use (lp: #1453174)

 -- Sebastien Bacher <email address hidden> Tue, 29 Sep 2015 11:48:31 +0200

The verification of the Stable Release Update for gvfs 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.