I use a simple keyfile on a USB key and have it backed up in various places. My kbdx. files are also backed up in various places. I assume that one day my home will be burgled or burn down. The effort involved in keeping these backups is negligible and I see no risk of losing access to my passwords in Keepass. However, although I am fortunately not a "Person of Interest" who could be under the radar of some security service with its expensive professional burglars and hackers, my residual concern...
I've been using KeePass for ages with a keyfile on a USB key. Now I'm reading about theYubikey and, despite reading numerous postings here and reading https://keepass.info/help/kb/yubikey.html I haven't grasped what the advantages of the Yubikey are because I can't understand the terminology with all its acronyms. I simply want to protect my passwords. If someone here can say clearly, for example, "Yes, Yubikey offers better protection than a simple keyfile" then I'll push on with my efforts to understand...
Possibly relevant here, possibly not.; applies to many "Can't log in, won't accept my password" problems: check that your computer is using the correct keyboard layout. Explanation: I kept having this problem with various logins and discovered that Windows 10 for some reason occasionally and silently changes the keyboard layout to US English from my local keyboard layout. So what I type in isn't what ends up in the login password slot. Just check the keyboard setting in Windows and, if necessary,...
You write "However, it doesn't sound like you have customized your keyboard layout". The OP may not have customised his/her keyboard layout. The keyboard layout may have been changed without his/her knowledge. I had a password problem (mentioned in another post here) and discovered that something was occasionally resetting my keyboard layout to English-US. I haven't yet discovered what that "something" is but wonder whether it is/was associated with a Windows 10 update. My keyboard-layout-reset problem...
Couldn't log in to KeePass with master password. Panic. Was absolutely sure that I had the correct password. Finally discovered that Windows had changed my keyboard to its default (Windows US). Changed back to the correct keyboard. Login problem solved. Windows 10 has subsequently spontaneously changed the keyboard several times. Am still trying to find out how/why.
Ha, ha. This silent changing of the keyboard has happened several times over, let's say, the last 12 months. I'm beginning to suspect - and will now be watching this more closely - that it happens when one of the not-infrequent Windows 10 updates occurs. That's one reason why I flagged it here. It's just possible that other Windows 10/KeyPass users have had the same problem (but some may have failed to identify this cause and simply given up on KeyPass or simply started another database).
I got this error message and after ages spent looking for the cause - I was afraid that the key file had been corrupted - I discovered the simple answer/solution: for some reason Windows 10 had silently reset my keyboard to the default US configuration so the passwords I was typing in weren't being registered in the correct form. Reset the Windows 10 keyboard setting to my local keyboard and - bingo ! - KeyPass was working again.