@Jurgen-Goedbloed I had a look through the code and I am fairly sure this is caused by the old code signing cert has lost validity on the 7th of September 2020. This cert is only used to ensure the binaries are certified by the FOG project team. We updated the code signing cert in January 2020 and released FOG 1.5.8 together with fog-client 0.11.19.
Unfortunately I kind of lost sight of this “major” change that would affect auto-updating after 7th of September 2020 and never officially announced that people should update earlier for the auto-update to work.
So from the version number we see in your log file I am sure you updated from FOG 1.5.7 to 1.5.9 - skipping the fog-client update that introduced the new code signing cert. This would have worked perfectly fine while the old code signing cert was still valid but fails now.
You’ll need to update all your fog-client installations to 0.11.19 (auto-update to 0.12.0 will work from there) or 0.12.0 through some other kind of software deployment mechanism I am afraid.
For now you should manually edit /var/www/html/fog/lib/fog/system.class.php and set FOG_CLIENT_VERSION back to 0.11.16 or clients will keep downloading the SmartInstaller.exe binary over and over again and put load on your FOG server for no reason. The code is smart enough to handle a situation where you have FOG_CLIENT_VERSION set to 0.11.16 version but the fog-client on some or all of your machines is on 0.12.0 already. So don’t worry about this.