Recently, I moved to a new computer and have been working to install all the software I previously used. KeePass has been indispensable; a wonderful program that I’ve used for years now. Fortunately, or not, opening KeePass in the past has been as simple as clicking on the icon and typing in my password. After backing-up all of my files from the old computer and moving them to the new, I installed KeePass 2.whatever and tried to open my kdbx file. Surprisingly, I got an error that “the composite key is invalid” even though I was sure I typed my password correctly.
The solution, for me at least, is that I was using key file (a separate file from the KeePass kdbx file that has a .key extension) as extra security, but it had been so long that I didn’t remember this detail.
Notice how the Key File field is unselected and “none”? This was my problem. When I initially setup KeePass years ago, I chose to create a .key file for more protection, but my new installation didn’t know this. Firstly, the .key file might be in the same directory as your .kdbx database file. If this is the case, just FYI, this is a TERRIBLE practice. You should never put your key file in the same place as your .kdbx; that’s like hanging the key to your front door on a hook next to your front door. Choose the browse folder next to the key file field, and navigate to the same directory as your kdbx:
Your files probably won’t have the same name, because you give them a specific name when you set them up. Also, if you don’t find a .key file in the directory with your .kdbx and are still having the problem, you might try to do a search on your computer for a .key file located somewhere else. It’s possible you specified a different location when initially setting up your password database.
Hope this helps you!