pkg_resources.DistributionNotFound: The 'pipenv==2018.10.13' distribution was not found and is required by the application

I had the same problem. You should reinstall pipenv using the same package manager you used the first time.

• If the installation was done using pip, then:

  pip uninstall pipenv
  pip install pipenv
  

• If you are using brew, then you must run the commands exposed by Andrei

  brew uninstall pipenv
  brew install pipenv
  

To check if pipenv installation was successfully completed, run: pipenv --version

From the comments, alternatively use:

brew reinstall pipenv

This should fix the problem too:

pipenv --rm
pipenv check
pipenv sync

I run into this problem from time to time when updating python using anaconda.