Maybe you use KeePass 1.x? KeePass 1.x does not support the new database format and saves its databases as KDB files. KeePass 2.x uses the new database format

Maybe you use KeePass 1.x? KeePass 1.x does not support the new database format and saves its databases as KDB files. KeePass 2.x uses the new database format (KDBX) and it can also import KDB databases created with KeePass 1.x. See the differences here: http://keepass.info/compare.html http://keepass.info/compare.html http://keepass.info/help/v2/version.html http://keepass.info/help/v2/version.html I use the same combination myself (KeePassDroid on Android, KeePassX 2 alpha on Linux, KeePass 2 on Windows) with a single KDBX database and I can read the database fine on all OSes. However, I avoid editing the database on Android and on Linux, since KeePassX 2 is still alpha, while KDBX support in KeePassDroid is still experimental.