I have several model of Mikrotik rpoduct, and I found there is a issue that the file store on Mikrotik routers will automatically be erased after a general reboot. To reproduce this issue, upload an arbitrary file then press reboot to reboot the device, check whether the file just uploaded is there.

RouterOS Version: 6.47.6

My result is that all files are missing after reboot on below model:
RouterBOARD 962UiGS-5HacT2HnT
RBcAPGi-5acD2nD

But it's working properly that files are still there after boot on below model:
RouterBOARD 951Ui-2HnD
RB4011iGS+5HacQ2HnD

Hopefully MikroTik technician can see my bug report, it's suffering me for a long time. Let me know if it's not right way to report a bug.

On some device models, files which should survive a reboot must be placed to a flash/ directory (from command line, you just use the flash/ prefix of the file name).

On some device models, files which should survive a reboot must be placed to a flash/ directory (from command line, you just use the flash/ prefix of the file name).

Tested, above answer is exactly correct.