Cannot update due to "Requires Installation of untrusted packages"

[dreamquartz]

Just received a new update.
17 files, total size: 7.2 Mb.

It cannot update as a result of: Requires installation of untrusted packages
The action would require the installation of packages from unauthenticated sources.

See attachment

All Setting, except under tab"Other Software, "Colonical Partners (Source Code)". are ticked.

Never had this happen before.
Does anyone know what this is?

[dreamquartz]

Bump

[oldos2er]

Can you run
sudo apt-get update in a terminal, and copy & paste all the output here?