Error message when refreshing keys

[Dr. Peter Voigt]

I am on 10.1-RELEASE (amd64) and have installed latest gpg 2.0.27
from ports. When issuing

# gpg --refresh-keys

operation seems to work but I am getting following error messages at
the end:

...
gpg: keyserver communications error: Not found
gpg: keyserver communications error: Bad public key
gpg: keyserver refresh failed: Bad public key

On an openSUSE machine I have installed gpg 2.0.22 and I have no such
error message.

Is this a know error? What does it mean? Is it FreeBSD specific? 

Any hints are appreciated.

Peter