Fatal: no entropy gathering module detected

RHEL 7
Cannot log in from the console
Using rd.break, able to get to a maintenance prompt
chroot /sysroot works
But after that, most commands only emit the string in the title.
Just some commands that have been tried:
passwd (since the root password appeared to be a problem)
systemctl (to inspect for the rngd service)
rpm ("failed to initialize NSS library")
ps
top

This is an in-place upgrade from RHEL6.

Any ideas would be welcome.

Thanks.

TimG