Some more information.
I could not start the update manager from Dash either. If I clicked the update manager from Dash, nothing happened.
update-manager was actually somewhere in the background:
$ sudo ps aux | grep update martijn 2844 0.0 0.0 403288 13512 ? Sl Jun14 0:01 update-notifier martijn 11622 0.0 0.8 761848 131560 ? SNl 07:58 0:04 /usr/bin/python /usr/bin/update-manager --no-focus-on-map
After killing the update-manager process I was able to start the update manager from Dash.
Some more information.
I could not start the update manager from Dash either. If I clicked the update manager from Dash, nothing happened.
update-manager was actually somewhere in the background:
$ sudo ps aux | grep update update- manager --no-focus-on-map
martijn 2844 0.0 0.0 403288 13512 ? Sl Jun14 0:01 update-notifier
martijn 11622 0.0 0.8 761848 131560 ? SNl 07:58 0:04 /usr/bin/python /usr/bin/
After killing the update-manager process I was able to start the update manager from Dash.