Quicken backups (*.qdf-backup) files can be recovered in Quicken should the user need it. This will basically restore the QDF file which you can in turn save in the program.
Convert Quicken financial data backup to Quicken financial data.
We found one software available in the database for this conversion.
Microsoft Windows software - convert qdf-backup to qdf on Windows
A personal finance management program by Intuit
Convert from qdf-backup file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.