First, minimal test ISO is uploaded for the September 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. Again, major changes to the installer Calamares will need to be thoroughly tested.

This ISO will feature Qt 5.13.0 or 5.13.1, Plasma 5.16.4, the Linux kernel 5.2.xx, Nettle 3.5.1, Libevent 2.1.11, Glib2 2.60.6 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 430 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 5.61.0, KDE Applications 19.08.0, Plasma 5.16.4 and Linux 5.2.1x 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-2019.08.27-x86_64.iso
sha256sum:

e65b89b72142e62fcb786a391f2f39dc35ced9028c05e99e83fd5c3e72901a13  KaOS-2019.08.27-x86_64.iso

On this ISO you will find:
Linux 5.2.10
systemd 242
gcc 8.3.0
Qt 5.13.0
Frameworks 5.61.0
Plasma 5.16.4
KDE Applications 19.08.0
Calamares 3.2.13
Octopi 0.9.0 with sysinfo & cachecleaner tool

Known issues:

Welcome page links in Calamares cannot open Falkon, QtWebengine no longer allows the root user to run sandboxed. This is known in Calamres upstream, work will start to no longer need to run Calamares as the root user, but won't be fixed in time for this ISO. Workarounds will be tried.