Hi!

It seems you ran into the error due to the incompatible falcon version. You should have falcon==0.3 installed for the setup to work for older Mailman versions.

However, this error doesn't occur with the latest Mailman version 3.1.0 So you should upgrade your Mailman version and the issue would be solved. You can pull the Mailman master branch from Gitlab and then re-run the setup.

Aditya.