Geary and other gnome-keyring users report that occasionally an error is returned when looking up passwords via dbus. This seems to be due to an error from gnome-keyring, rather than say libsecret. The password is not actually forgotten, it's just that gkd encounters and reports some error.

A recent error from gkd, as reported by libsecret, looks like this:

>  org.freedesktop.DBus.Error.Failed: Couldn't create item: The secret was transferred or encrypted in an invalid way.

The latter string is found in daemon/dbus/gdk-secret-objects.c in the cleanup of collection_method_create_item().

For some background, Geary is using libsecret's secret_password_lookup() method to retrieve passwords, using the SECRET_SCHEMA_COMPAT_NETWORK schema. In the case above, this password was possibly the first of three accounts that would have needed password lookups, and the second two accounts were able to lookup their secrets without error.

The Geary bug report is here: https://bugzilla.gnome.org/show_bug.cgi?id=714128, and this issue has been reported downstream in both Ubuntu: https://bugs.launchpad.net/ubuntu/+source/gnome-keyring/+bug/1221955 and Debian: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=659036, at least.