Cannot start after upgrade

[Stefano Facchini <stefano facchini gmail com>]

Hi,

after a recent upgrade I can't start gnome-shell anymore. When I try 
"gnome-shell --replace" I obtain

Avviso del window manager: Log level 16: Accessibility: org.a11y.atspi 
schema not found. Are you sure that at-spi or at-spi2 is installed on 
your system?
Avviso del window manager: Log level 16: Accessibility: invalid module 
path (NULL)
Avviso del window manager: Log level 16: Accessibility: error loading 
the atk-bridge. Although the accessibility on the system is enabled and 
clutter accessibility is also enabled, accessibility support on GNOME 
Shell will not work
Avviso del window manager: Log level 16: cannot register existing type 
`GdkWindow'
Avviso del window manager: Log level 8: g_once_init_leave: assertion 
`initialization_value != 0' failed
**
ERROR:gi/object.c:1256:gjs_define_object_class: assertion failed: (gtype 
!= G_TYPE_INVALID)
Shell killed with signal 6

Is there anything I can do?

thanks