I know it's a uncurated app so I don't really expect this question to be answered, but the fact of the matter is I just installed KeePass from the Application Center, created a database with just a Master Password (no KeyFile) containing just one entry, saved it on the system disk, closed it (for some reason it insisted on saving it again even though I hadn't touched it since the first save), and then couldn't open it again (database corrupted or password wrong).
On checking the GitHub repository I found that this "issue" (astonishingly embarrassing blunder I would call it) was fixed in KeePass 2.2.4, and the Application Center had given me 2.0.3. So I deleted it, went to apt-cache search and found no less than 3 versions available: keypass2, keypassx & keypassxc. Comments on AskUbuntu by a more diligent user than me however indicated that only the latter was still being updated regularly, so I installed it and it works.
Bottom line: Uncurated is one thing, but totally untested is quite another, and now I'm no longer sure that I can trust any uncurated apps from the Application Center. That is really not acceptable!