I had a strange effect with the v1.20.0-rc.1.
The Kastelo installations that further stored on 2 of my Synology servers, each with an exchanged binary in order to be able to carry out internal updates. As a result, there was no synchronization on both servers at the same time, I only noticed this later after the update.
I also installed a parallel installation of SynoCommunity on both servers in order to be able to carry out local, i.e. internal, synchronizations. These continued to run with v1.20.0-rc.1 without any problems.
Nevertheless, I set the “upgradeToPreReleases” parameter to false for all installations and reactivated v1.19.2 (was still there as Syncthing.old). Now everything works perfectly again, as before.
There were no problems on other Windows 10/11 and Android devices either. I just want to report this.
What is different about the v1.20.0-rc.1 that this can happen?