Server Freeze When Backing Up Windows Image Files

Currently running UrBackup Server Version 2.0.38 with UrBackup Client Version 2.0.36.
Both are running linux ubuntu 14.04 server edition.
The file backup freezes at 13% (~200GB of 2.2TB) and stops all other in progress backups before it freezes the whole server, causing me to reboot the server. I’ve looked into it and discovered that it keeps freezes on a windows image file (.vhdx). Is the backup freezing because of the amount of data, is it freezing because of the windows image backup file, or is there something else going on that I am missing?

If it “freezes” the whole server it is most likely an OS issue and not an UrBackup issue. What file system are you using for backup storage?

Linux Extended (ExFAT)