Rock5B With Debian image loaded in 16G eMMC module

Installed Debian in 16GB eMMC module. Module connected J8-1 at back of Rock5B. Debian booted fine. But when I tried “sudo apt update”, I got

rock@rock-5b:~$ sudo apt-get update
Reading package lists… Done
E: List directory /var/lib/apt/lists/partial is missing. - Acquire (30: Read-only file system)
W: Problem unlinking the file /var/cache/apt/pkgcache.bin - RemoveCaches (30: Read-only file system)
W: Problem unlinking the file /var/cache/apt/srcpkgcache.bin - RemoveCaches (30: Read-only file system)

I tried both in standalone and ssh, same results.

Please advise.

Thanks

Interesting, after power cycle, everything was fine. Strange!!!.