https://github.com/flathub/org.keepassxc.KeePassXC/issues/29
A keepassxc moderator said flatpak browsers are sandboxed and impossible to use keepasxc on...:
"In this case the problem is that you are using an isolated Firefox instance (Flatpak version). In other words, you currently must use a native (traditional) distribution package for Firefox. That is a package that is not sandboxed.
Here are the limitations of the current working solution in more detail:
Firefox must be able to write to its usual home directories, i.e. ~/.mozilla, in the real home directory.
Firefox (or KeePassXC-Browser if you will) must be able to launch keepassxc/keepassxc-proxy (effectively the same thing, since both are packaged as org.keepassxc.KeePassXC).
That means Firefox must be able to launch another app, i.e. from the host, which is not possible from within the sandbox. Allowing it to do so unacceptable, which is why Firefox cannot be sandboxed.
The path used to launch org.keepassxc.KeePassXC must be a single absolute path (no spaces allowed), i.e. no flatpak run org.keepassxc.KeePassXC. This is not a problem since Flatpak exports wrappers (by default in /var/lib/flatpak/exports/bin)."
I refuse to believe this information. i don't believe it. KeepassXC ran flawlessly on my ungoogled-chromium flatpak up until 2 week ago so this can't be true.
In case it is true🙂 and my case is the WEIRD ONE (it always is) then on that same thread I found this:
"Anyone who searchs for a workaround:
"Create a wrapper script /var/lib/flatpak/exports/bin/org.keepassxc.KeePassXC.proxy with the following content:
#!/bin/sh
exec /usr/bin/flatpak run --command=keepassxc-proxy org.keepassxc.KeePassXC "$@"
Make the script executable with chmod +x and then change the Use a custom proxy location to point this script."
Once I can translate how to do this in a way my chimpanzeean brain can decipher I will try it. what's a 'wrapper script'? how do I make?
another chimed in "This worked, thank you!
I had to make one small change though, since my Firefox config file (~/.mozilla/native-messaging-hosts/org.keepassxc.keepassxc_browser.json) contained the path without .proxy. So I named the file: /var/lib/flatpak/exports/bin/org.keepassxc.KeePassXC"