Thanks for your reply. I am using FTM 2019 and installed the latest update. The backup file was created with FTM 2019 so the application and the file should be compatible.
I did uninstall the App and re-install it and also the latest update. I think you may be correct though about the App being the problem. It might also be linked to the NAS communications.
Does anyone know if "Error Not enough space on disk drive" a windows error message, an application error or a system error? I am experiencing this on my Infinity laptop when I try to restore a "Family Tree Maker Backup (FTMB File)" into my Family Tree Maker application. I have 16 Gb of RAM & 790...