Build process for Ubuntu is failing -> Unable to download boot image

Problem:
After upgrading from Foreman 3.2 to 3.3 the build process for Ubuntu (20.04) is not working anymore

Expected outcome:
The rebuild should work like before

Foreman and Proxy versions:
Foreman 3.3.0

Foreman and Proxy plugin versions:

Distribution and version:
CentOS Linux release 7.9.2009

Other relevant data:
Failed to generate ISO image for instance xxx: ERF42-8486 [Foreman::Exception]: Unable to download boot file http://archive.ubuntu.com/ubuntu/dists/focal/main/installer-amd64/current/legacy-images/netboot/ubuntu-installer/amd64/vmlinuz, HTTP return code 404

I checked the download directory and the compressed image is not stored in this directory.

I guess the problem is related to:

I chaned the file:
/usr/share/foreman/app/models/operatingsystems/debian.rb

  • if (guess_os == ‘ubuntu’ && (major.to_i > 20 || major.to_i == 20 && minor.to_i >= 3))
  • if (guess_os == ‘ubuntu’ && (major.to_i > 20 || major.to_i == 20 && minor.to_i >= 5))

For Ubuntu 20.04 I need to load ‘linux’ not ‘vmlinuz’.
We are only using LTS versions so I do not know what is going on with 20.10.