Comment 1 for bug 1875055

The problem is:

20.04 comes with ruby 2.7, but puppet is not yet compatible with ruby 2.7. See upstream

https://tickets.puppetlabs.com/browse/PUP-10247

Puppetlabs say in https://tickets.puppetlabs.com/browse/PUP-10467

This appears to be an issue with the native Ubuntu package? Our Puppet Agent package (contains its own Ruby) should be available soon (nightlies are up now - https://nightlies.puppet.com/apt/pool/focal/ ). Puppet itself is not fully working with Ruby 2.7 yet (https://tickets.puppetlabs.com/browse/PUP-10247), but that work is also underway.

That's the problem. Puppet and Ruby2.7 not compatible yet.

I can run the master smoothly when running in a docker image built with ruby 2.6, but I haven't found a decent solution for the client/agent yet.