As of Dragonfly 3.1, if you encounter immediate crashes when starting Dragonfly, and you're running on a Dell computer, you may be experiencing a known issue as described here:
https://www.dell.com/community/en/conversations/productivity-software/backup-and-recovery-causing-applications-using-qt5-dlls-to-crash/647f54c6f4ccf8a8dee57b89
The solution is to upgrade or uninstall the Dell Backup and Recovery component.