after receiving this error I ran:
wget http://security.ubuntu.com/ubuntu/pool/main/c/ca-certificates/ca-
certificates_20170717~16.04.1_all.deb
Then I ran:
dpkg -i ca-certificates_20170717~16.04.1_all.deb
and finally:
dpkg --configure -a
which unpacked 20180409 over 20170717~16.04.1
However,
Public bug reported:
Doing a 'do-release-upgrade', I received this error near the end. The
install/upgrade did not finish as a result.
ProblemType: Package
DistroRelease: Ubuntu 18.04
Package: ca-certificates 20180409
ProcVersionSignature: Ubuntu 4.4.0-174.204-generic 4.4.211
Uname: Linux 4.4.0-1