it looks like due to recent Python updates there’s a problem with aurman. You can not use aurman anymore and get errors if you start aurman.
The problem got fixed for the package from the AUR, however not the version from the repo of antergos.
Looks like aurman from the Antergos repo is still on version 2.16.10-1.
aurman from the Antergos repo.
As a workaround it’s possible to install aurman from the AUR with
yaourt -S aur/aurman