I tested an upgrade from Bionic to Focal with -proposed enabled (I had to remove the disabling of -proposed in DistUpgradeController.py) and did not encounter any of the following error messages:
GLib-GObject-WARNING **: specified class size for type 'PangoCairoFcFont' is smaller than the parent type's 'PangoFcFont' class size at /usr/lib/x86_64-linux-gnu/perl5/5.30/Glib/Object/Introspection.pm line 67.
GLib-GObject-CRITICAL **: g_type_add_interface_static: assertion 'G_TYPE_IS_INSTANTIATABLE (instance_type)' failed at /usr/lib/x86_64-linux-gnu/perl5/5.30/Glib/Object/Introspection.pm line 67.
GLib-CRITICAL **: g_once_init_leave: assertion 'result != 0' failed at /usr/lib/x86_64-linux-gnu/perl5/5.30/Glib/Object/Introspection.pm line 67.
GLib-GObject-CRITICAL **: g_object_new_valist: assertion 'G_TYPE_IS_OBJECT (object_type)' failed at /usr/lib/x86_64-linux-gnu/perl5/5.30/Glib/Object/Introspection.pm line 67.
I had seen them when I tried upgrading the same virtual machine when -proposed was not enabled. Attached you'll find my apt-term.log from the successful upgrade.
I tested an upgrade from Bionic to Focal with -proposed enabled (I had to remove the disabling of -proposed in DistUpgradeCont roller. py) and did not encounter any of the following error messages:
GLib-GObject- WARNING **: specified class size for type 'PangoCairoFcFont' is smaller than the parent type's 'PangoFcFont' class size at /usr/lib/ x86_64- linux-gnu/ perl5/5. 30/Glib/ Object/ Introspection. pm line 67. CRITICAL **: g_type_ add_interface_ static: assertion 'G_TYPE_ IS_INSTANTIATAB LE (instance_type)' failed at /usr/lib/ x86_64- linux-gnu/ perl5/5. 30/Glib/ Object/ Introspection. pm line 67. x86_64- linux-gnu/ perl5/5. 30/Glib/ Object/ Introspection. pm line 67. CRITICAL **: g_object_ new_valist: assertion 'G_TYPE_IS_OBJECT (object_type)' failed at /usr/lib/ x86_64- linux-gnu/ perl5/5. 30/Glib/ Object/ Introspection. pm line 67.
GLib-GObject-
GLib-CRITICAL **: g_once_init_leave: assertion 'result != 0' failed at /usr/lib/
GLib-GObject-
I had seen them when I tried upgrading the same virtual machine when -proposed was not enabled. Attached you'll find my apt-term.log from the successful upgrade.