Same class of errors. Been happening almost forever. Computer has been rebooted in past week. Computer has had its Ubuntu version upgraded since 2015. non-standard Packages installed often in use: Skype (current beta) SciTE text editor KeePass2 (from repo in previous Ubuntu version) user@computer:~$ uname -a Linux computer 4.4.0-101-generic #124-Ubuntu SMP Fri Nov 10 18:29:59 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux Dec 4 09:54:45 computer org.gnome.zeitgeist.SimpleIndexer[2111]: ** (zeitgeist-fts:2968): WARNING **: Unable to get info on application://nautilus-autostart.desktop Dec 4 09:54:45 computer gnome-session[2366]: ** (zeitgeist-datahub:2948): CRITICAL **: string_strip: assertion 'self != NULL' failed Dec 4 09:54:45 computer gnome-session[2366]: (zeitgeist-datahub:2948): Gtk-CRITICAL **: gtk_recent_info_get_application_info: assertion 'app_name != NULL' failed Dec 4 09:54:45 computer gnome-session[2366]: ** (zeitgeist-datahub:2948): WARNING **: recent-manager-provider.vala:106: (null) was not registered in RecentInfo item 0x1689620 Dec 4 09:54:45 computer gnome-session[2366]: ** (zeitgeist-datahub:2948): CRITICAL **: string_strip: assertion 'self != NULL' failed Dec 4 09:54:45 computer gnome-session[2366]: (zeitgeist-datahub:2948): Gtk-CRITICAL **: gtk_recent_info_get_application_info: assertion 'app_name != NULL' failed Dec 4 09:54:45 computer gnome-session[2366]: ** (zeitgeist-datahub:2948): WARNING **: recent-manager-provider.vala:106: (null) was not registered in RecentInfo item 0x167d030 Dec 4 09:54:45 computer gnome-session[2366]: ** (zeitgeist-datahub:2948): CRITICAL **: string_strip: assertion 'self != NULL' failed Dec 4 09:54:45 computer gnome-session[2366]: (zeitgeist-datahub:2948): Gtk-CRITICAL **: gtk_recent_info_get_application_info: assertion 'app_name != NULL' failed Dec 4 09:54:45 computer gnome-session[2366]: ** (zeitgeist-datahub:2948): WARNING **: recent-manager-provider.vala:106: (null) was not registered in RecentInfo item 0x16977f0 Dec 4 09:54:45 computer gnome-session[2366]: ** (zeitgeist-datahub:2948): CRITICAL **: string_strip: assertion 'self != NULL' failed Dec 4 09:54:45 computer gnome-session[2366]: (zeitgeist-datahub:2948): Gtk-CRITICAL **: gtk_recent_info_get_application_info: assertion 'app_name != NULL' failed Dec 4 09:54:45 computer gnome-session[2366]: ** (zeitgeist-datahub:2948): WARNING **: recent-manager-provider.vala:106: (null) was not registered in RecentInfo item 0x1697690 Dec 4 09:54:45 computer gnome-session[2366]: ** (zeitgeist-datahub:2948): CRITICAL **: string_strip: assertion 'self != NULL' failed Dec 4 09:54:45 computer gnome-session[2366]: (zeitgeist-datahub:2948): Gtk-CRITICAL **: gtk_recent_info_get_application_info: assertion 'app_name != NULL' failed Dec 4 09:54:45 computer gnome-session[2366]: ** (zeitgeist-datahub:2948): WARNING **: recent-manager-provider.vala:106: (null) was not registered in RecentInfo item 0x1697530 Dec 4 09:54:45 computer gnome-session[2366]: ** (zeitgeist-datahub:2948): CRITICAL **: string_strip: assertion 'self != NULL' failed Dec 4 09:54:45 computer gnome-session[2366]: (zeitgeist-datahub:2948): Gtk-CRITICAL **: gtk_recent_info_get_application_info: assertion 'app_name != NULL' failed Dec 4 09:54:45 computer gnome-session[2366]: ** (zeitgeist-datahub:2948): WARNING **: recent-manager-provider.vala:106: (null) was not registered in RecentInfo item 0x16973b0 Dec 4 09:54:45 computer gnome-session[2366]: ** (zeitgeist-datahub:2948): CRITICAL **: string_strip: assertion 'self != NULL' failed Dec 4 09:54:45 computer gnome-session[2366]: (zeitgeist-datahub:2948): Gtk-CRITICAL **: gtk_recent_info_get_application_info: assertion 'app_name != NULL' failed