Unable to upgrade using Attended Sysupgrade or auc

There is an error when I tried to upgrade the snapshot from r23147 to newer ones for BananaPI BPI-R3. I am not sure it is just me.

The error message with auc:

......
Downloading file:packages/Packages.sig
Signature check failed.
Remove wrong Signature file.
Collected errors:

Upgrade how, and what ?

Is this pre, or post upgrade?