First, minimal test ISO is uploaded for the October stable ISO release.

provide the installation log, if you encounter any issue at all

As always, early test ISOs are minimal, very few apps, just a web-browser, file manager, text editor, GUI package manager. The non-free nvidia drivers are included since they are a big part of what needs testing. New Systemd is the biggest hurdle so far in this test cycle, it has shown major bugs with Linux 5.3 on some hardware, but hard to replicate.
This is a very first ISO that is complete python2 free.

This ISO will feature Qt 5.13.1 or 5.13.3, Plasma 5.17.0, the Linux kernel 5.3.xx, GCC 9.2.0, Glibc 2.30, Glib2 2.62.1 and Systemd 243 among the many updates. Non-free installs feature a different presentation of the License page, help is needed to test this with newer Nvidia cards using the 435 series drivers.

KaOS ISOs are not only GTK free but are Qt4 & KDE 4 free too.
This is as pure a Qt 5/Plasma 5 ISO as possible.

Plan is to have Frameworks 5.63.0, KDE Applications 19.08.2, Plasma 5.17.x and Linux 5.3.x on the final ISO. If all testing goes well expect the final ISO to be released within a week to ten days

Calamares version used is 3.2.13 Release Notes page is only partially updated.

The ISO is using packages from the build repo, but that repo is not enabled, so if you decide to install, make sure to add the build epo to your pacman.conf.

To help with testing:

Use a GPT partition table on BIOS system (manual partitioning)
Use Isowriter to write the test ISO to your USB stick, plan is to remove imagewriter from the repos after this test cycle
Use in live mode on as much different hardware as possible
If you have an UEFI capable system, check if the ISO boots in both UEFI and legacy BIOS mode, make sure though to turn off secure boot
test installs on real hardware are needed, not just vbox
check as many partitioning options as possible in the partitioning of Calamares, see if all works and is clear enough
test with the BTRFS filesystem, it should now work properly without any intervention on UEFI systems (systemd-bootloader).

debug packages for Calamares are part of all ISOs, run Calamares with gdb if you encounter errors
provide the installation log, if you encounter any issue at all

You can start Calamares from the Welcome app, or run it with:

sudo calamares -d

The install log will be created in the home directory of the Live user, see ~/installation.log. It is available after the install in the target system in /var/log/installation.log
If run from cli, make sure to pastebin the full output, since no installation.log will be copied then, though that log is more complete.

The site for testing ISOs in use:
https://sourceforge.net/projects/kaos-test/files/iso/
https://sourceforge.net/projects/kaos-test/files/iso/KaOS-2019.10.16-x86_64.iso
sha256sum:

ce1a142be73310b20f243f6ad6f353b665d87a21e2c8916debb77a12115a1cfa  KaOS-2019.10.16-x86_64.iso

On this ISO you will find:
Linux 5.3.6
systemd 243
gcc 9.2.0
Qt 5.13.1
Frameworks 5.63.0
Plasma 5.17.0
KDE Applications 19.08.2
Calamares 3.2.13
Octopi 0.9.0 with sysinfo & cachecleaner tool

Known issues:

~~ISO might not boot into a plasma session for some AMDGpu graphics cards, needs to be confirmed.~~
Non at this time