Hello, every time I restart my routerboard, I lose the backup file that was saved in the folder. It's as if the system deletes the file every time the routerboard is turned off or restarted. Does anyone know how to fix this?
Which device model in particluar?
Some device models (mainly those with less than 32MB of flash and more than 64MB of RAM) have their "storage root" on RAM disk ... and contents of that file system obviously can't be kept over reboots. A feature, which points out such device is presence of /flash directory in files root. Non-volatile storage (what remains of it) is mounted under that directory. Devices which don't user RAM disk as root of their storage, don't have flash directory.
A notable example of such devices is hAP ac2.
A note on storing backups: IMO backups should be immediately saved off device. Because they are often needed after device crashes ... and it might take backup files with it.
hello,
The model is RB750Gr3
So try to put your backup file inside the /flash directory and see if the issue repeats
Hi,
where exactly do you save tha backup to?
I guess that it is saved to RAM, not to flash drive so it disappears after reboot.
EDIT: Normis wast faster than me 
Yup, hEX Gr3 is one of those 16MB flash devices with RAM disk as root of storage. Depending on backup file size there might not be enough free space on /flash ...
I placed it in the /flash directory and it worked. Thanks everyone!