dpkg gnome-settings configuration errors after installing gnome 40 on Ubuntu 21.10

This is a known bug #1935767.

Take a look at comment-3 by Paul Broadhead:

I have a manual fix for this.

Edit "/var/lib/dpkg/info/vanilla-gnome-default-settings.postinst"

Change "gdm3-theme.gresource" to "gdm-theme.gresource"

Then "sudo apt install -f"

The vanilla gnome setup now works as expected.

You can fix it as follows.

1. Open /var/lib/dpkg/info/vanilla-gnome-default-settings.postinst with a text editor.

2. Find gdm3-theme.gresource and replace it with gdm-theme.gresource

3. Run sudo apt -f install to fix.

Alternatively, here is a copy-paste friendly one line version of the above steps:

sudo sed -i "s/gdm3-theme.gresource/gdm-theme.gresource/" /var/lib/dpkg/info/vanilla-gnome-default-settings.postinst && sudo apt -f install