Plugin Install: failed to properly resolve required dependencies

Whenever I try to install a plugin (doesn’t matter what) it always fails with this message:

Install local plugins (Y/N) [N]: y
Installing the 'vagrant-hosts' plugin. This can take a few minutes...
Vagrant failed to initialize at a very early stage:

Vagrant failed to properly resolve required dependencies. These
errors can commonly be caused by misconfigured plugin installations
or transient network issues. The reported error is:

conflicting dependencies childprocess (= 3.0.0) and childprocess (= 4.0.0)
  Activated childprocess-4.0.0
  which does not match conflicting dependency (= 3.0.0)

  Conflicting dependency chains:
    childprocess (= 4.0.0), 4.0.0 activated

    childprocess (= 3.0.0)

  Gems matching childprocess (= 3.0.0):

I have no plugins currently installed:

vagrant plugin list
No plugins installed.

Vagrant is installed using my OS’s (FreeBSD) package manager. It is on the latest version (as of this post FreshPorts -- sysutils/vagrant: Vagrant Virtual Machine Manager) :

vagrant --version
Vagrant 2.2.14