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