Little bug
I do update
Versions OPNsense 15.7.7_1-i386
FreeBSD 10.1-RELEASE-p16
OpenSSL 1.0.2d 9 Jul 2015
Then check next update and have message
"No active remote repositories configured."
go to the System: Settings: General, reselect "Firmware Mirror" and all worked.
I found the root cause... Fixed in time for 15.7.8, thanks!
https://github.com/opnsense/core/commit/8061ea1e5b9af23399e510dd87668ba06340cbff