"Unable to open the database. Invalid database file (error no 6). Line 1516, column 475"
Greek to me. I can open the .kdbx file on my iPad, using iKeePass v.2.6.0 (75). My Mac (OS X 10.9.2), however, will not open the file. I recently updated to KeePassX 2.0 alpha 5, but I went back to alpha 3 because that was the last iteration that would open the file...although, now alpha 3 won't open that one file. Nor will KeePass2Android (v 0.9.3-release-3). Mac will open other, older KeePassX databases. Luckily, I have backups (actually, earlier iterations that have most of the data). Wouldn't mind knowing what went wrong, though.
Oh yeah. I store the dbs on Dropbox.
I think the simple answer is the file is corrupted...who knows why. But isn't there a way to try to fix a busted file?