KeePassX uses an older database format (KDB) than KeePass 2.x (KDBX4). It also lacks AEAD and is actually less secure than KDBX4 according to the analyses I've read.
Just a general info: KeePassX can read and write the KeePass2 file format, but you have to checkout the git repo manually. It works for me since at least one year.
The problem is the current maintainer, it seems that he has no interest in releasing a new version :(
