Can't install Syncthing b/c of "release file"

[njoseph]

Duplicate of Error installing apps after fresh install of FreedomBox

You can either modify your /etc/apt/sources.list as stated in this answer -

Error installing apps after fresh install of FreedomBox

All the newly built stable images (announcement pending) seem to have bullseye-security listed in the sources.list. So, there is no problem there. It is also best if users use bullseye everywhere in the sources.list instead of stable to allow FreedomBox to automatically upgrade to next stable release bookworm in 2 years in controlled manner. A typical sources.list file should look like: deb http://deb.debian.org/debian bullseye main deb-src http://deb.debian.org/debian bullseye main deb http:…

Or install the latest Pioneer image built for Debian 11 (Bullseye) from here:
https://ftp.freedombox.org/pub/freedombox/pioneer/weekly/