I installed my new Windows, so i wanted to import my passwords. I saved a .kdbx file. I tried to import, but it said:
Failed to load the specifed file!
The composite key is invalid!
Make sure the composite key is correct and try again.
Can anybody help me? Sorry for my english I am from Germany.
I fixed it!
Solution: The Key File must be selected!
The particular error that you are reporting means that you are using the wrong Master Key when attempting to open the database.
If you are using KeePass 2.x on both machines, you don't need to import your passwords. You will be able to open the password database (.kdbx file) on the new installation, provided that you supply the correct Master Key of your password database (.kdbx file). Depending on how you originally configured the Master Key for your database, in addition to the correct Master Password, you may need a Key File; and/or you may need to unlink the database from the original Windows User Account before opening the file under the new windows user account.
To check that you are using the correct Master Key:
Glad to hear that you figured it out yourself.