This is actually mentioned in their FAQ ĭue to Snap's isolation and security settings, you cannot access any files outside your home directory. So if you want to use sshfs or any other such tech for syncing, it's better to use e.g.

The snap-packaged version doesn't connect well to externally mounted filesystems. KeepassXC on Ubuntu (and on other Linuxes) Here are some things to watch out for with KeepassXC and Keepass2Android: Regardless of which technology you choose you should also make backups synchronization is not backup and sync can get it wrong and wipe your stuff. However in my experience Syncthing has corner cases of its own. One other option is to use Syncthing to sync the databases. Keepass2Android on the other hand has built in support for sftp, WebDAV and a number of magic folder solutions (DropBox, OneDrive et al.)

Maybe the wording is unfortunate, but it seems in the screenshot above that you have to choose between compatible or safe for 'Dropbox, etc' I understand that they do not want to clutter the app with syncing code, but my guess is that there will be corner cases depending on the sync technology chosen. It relies on external solutions doing that such as sshfs, DropBox and so on. KeepassXC doesn't have any syncing capabilities of its own. I then tested to change number of rounds of key derivation on the Linux side, and that propagated fine to Android. Update: I just tested changing memory hardness of Argon2 key derivation on the Android side, and it propagated fine to Linux. In initial tests so far, the syncing seems to work. KeepassXC is a community rewrite of KeepassX, and Keepass2Android is recommended for Android on the site of KeepassXC. Here I am testing KeepassXC (on Ubuntu but should be the same for most Linux distros, also available for Windows and MacOS) and Keepass2Android. Often you want to use the same credentials on several of your devices and hence you need to be able to sync. Most of it, possibly all, is open source. Keepass is originally a Windows based password manager that has grown into an ecosystem of several Keepass-compatible password managers and also plugins based on the kdbx file formats, and some protocols.

Keepassxc dropbox