Migration stopped at Error "Backup version file is missing or empty"
Secondary Authentication Password for the backup file is not provided.
The backup file has been renamed.
Make sure downloaded backup has the same extension as it's under Online Backups or on the Archive Server.
Make sure the filename of the downloaded backup file is the same.
The backup file will have a .zip2 extension if secondary encryption has been used for backup in version 2.4/2.3.
Upload the .zip2 file and input the secondary encryption password then start migration.