If it is not checked nothing is established. but not proved, that you were not using a key file. ) checked in Tools>Options.>Advanced(tab)>Advanced(section)?.

Is Remember key sources (key file paths, provider names.

Is the key file box checked on the Enter Master Key dialog? If the box is checked you are using a key file, if it is not checked nothing is established.

The master key of the database included a key file component, and the key file is missing, damaged, or changed.

You have recently or accidentally changed to a different keyboard layout.

Make sure the password is entered correctly and there are no leading or trailing spaces.

Press the reveal password button to the right of the Master Password field on the 'Enter Master Key' dialog.

The user is entering the wrong master password.

What file Size in KB is listed for the database? Saving a database is different than closing/locking a database or exiting KeePass. Is the date modified on the file recent? It should have a Date modified timestamp that corresponds to the last time the database was saved.

Navigate to the database using windows file explorer (Win+E).Try opening the database via the KeePass File>Open Recent menu item. Verify the database path listed on the error message is correct (see the attached example).The user is trying to open the wrong database.Carefully rule out every possibility below. Following is a list of the possible reasons for this error and some troubleshooting suggestions. It is unlikely that the 'Master key is invalid' error is wrong. Have you recently made any changes to KeePass or its installation? Don't reinstall KeePass, it is unlikely to fix your problem, and it will complicate troubleshooting.

See the KeePass Master Key documentation for more information. The database master password is a database master key component.

Keepass windows user account