I resolved the issue on my system by manually reverting to the previous
debs for texlive-base and for texlive-binaries and its dependencies.
When I tried to re-run the upgrade to get more detailed info about the
lua error for this bug report, I found that the packages will now not
install at all: when I do 'apt-get dist-upgrade', it hangs at the stage
of generating the context formats.
The lua error involved complaining about something being ‘a nil value’;
I’m sorry I can’t be more specific, since I can no longer get the
problematic packages to install to reproduce the error.
Below /var/lib/texmf/web2c you should find some log files reporting