Comment 2 for bug 1952803

You did good analysis identifying the file permissions issue.

Cubic version 21.11-62 checks if Ubiquity is installed in the customized OS.
If it is, then the Packages page is shown to the user.
The Packages page allows you to select which packages Ubiquity should remove for a typical or minimal install.
If Ubiquity is not installed, the Packages page is bypassed.

The previous version of Cubic (version 21.11-61) did not do this check; it always showed the Packages page, even though the Packages page is unnecessary if without the Ubiquity installer.

Cubic uses the dpkg database to read package versions, and it expects this database to be readable by all. (It's similar to if you were to execute `dpkg -l cubic` without sudo. You would still get a result, even though you were a non-priviledged user).

I did a test using ubuntu-20.04.3-desktop-amd64.iso to install and run Cubic. I tried to customize ubuntu-18.04.5-server-amd64.iso.

I did not experience this bug. Instead, this was my output:

    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    Create new file system manifest file
    • Write file system manifest to.......... /home/ubuntu/Ubuntu/custom-
                                            disk/install/filesystem.manifest
    • Is Ubiquity installed?................. No
    • Show the Packages page?................ No
    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

In my test, I did not have a file named "custom-root/etc/apt/apt.conf.d/local", so this must be something unique/specific to your customizations. The dpkg database is located at "custom-root/var/lib/dpkg", so make sure this directory and its files are also readable by all (except the lock files which must have -rw-r----- permissions).

I'm curious why the permissions on your files are 640. I have 644 for the files in my test.
Did you make changes that would have caused this?