OK to upgrade working linuxCNC from Mint 19 to 20?

I have a working install of LinuxCNC on Mint 19.latest. Can I upgrade that to Mint v20 or does this require a complete reinstallation?

You can but it will require creating a snapshot of the existing system, downloading a lot of stuff that is usually much more than 2GB of the ISO image and will in total last much longer. I did try it but the moment it told me to create a snapshot i just inserted the Mint20 USB and proceeded on a new install and never looked back.
Do make a copy of the configs and other comps if you have any in use.

when i tried compiling linuxcnc in mint 20 I noticed it seems python 2 was called python2 rather then python - which breaks the build system.
Did you try compiling linuxcnc?

RIP builds fine and passes all tests. Building packages fails.
Personally I’d stay with 19.x
It’s still LTS.
Mixing in Debian packages on a Mint system gives issues with building and installing the Linuxcnc dev package. Ideally you want all your packages from the same ecosystem.

Hmm interesting -i'll investigate further.

I'd like to add that I was only trying with v2.9.
I think there might be a need for a stanza for Mint20 in debian/rules. (The lsb_release values for Mint 20 are a tad different to Mint 19.x)

Is there a way to pass or override values with debuild ?