Running Django locally with heroku fails due to missing Procfile

Question

I have a Django 1.11/Python 3.5 app that I built and want to run on Heroku locally. It's a simple SPA using the Heroku Django template provided on GitHub (https://github.com/heroku/heroku-django-template). I followed a Heroku tutorial (https://devcenter.heroku.com/articles/deploying-python#how-to-keep-build-artifacts-out-of-git), but I cannot seem to run the app locally using the following command:

heroku local web

Running this produces the following error:

return binding.open(pathModule._makeLong(path), stringToFlags(flags), mode);
                 ^

Error: EACCES: permission denied, open '.env'
    at Object.fs.openSync (fs.js:584:18)
    at Object.fs.readFileSync (fs.js:491:33)
    at loadEnvsFile (/snap/heroku/414/lib/node_modules/heroku-cli/node_modules/foreman/lib/envs.js:133:15)
    at Array.map (native)
    at loadEnvs (/snap/heroku/414/lib/node_modules/heroku-cli/node_modules/foreman/lib/envs.js:148:30)
    at Command.<anonymous> (/snap/heroku/414/lib/node_modules/heroku-cli/node_modules/foreman/nf.js:72:16)
    at Command.listener (/snap/heroku/414/lib/node_modules/heroku-cli/node_modules/commander/index.js:301:8)
    at emitTwo (events.js:106:13)
    at Command.emit (events.js:194:7)
    at Command.parseArgs (/snap/heroku/414/lib/node_modules/heroku-cli/node_modules/commander/index.js:615:12)

My .env file looks like this:

WEB_CONCURRENCY=3
SECRET_APP_KEY="xxxxxxxxxxxxxxxxxxxx"

I ran chmod 777 on .env but I get the same error.

When I run the following command:

heroku local

I get the following error:

[WARN] EACCES: permission denied, open 'Procfile'
[FAIL] No Procfile and no package.json file found in Current Directory - See run.js --help
 ▸    Cannot convert undefined or null to object

My Procfile looks like this:

web: gunicorn personal_website.wsgi

Now I cannot understand why when running "heroku local web" I get the previously mentioned error, especially after giving it the necessary permissions.

Also, others have had the same error when running "heroku local", but the answer is to "make sure the formatting of your Procfile is correct." Well mine is correct and have tried many variations to it.

I have seen others with this issue on SO and some have been resolved, unfortunately for me none of them worked.

What could I possibly be doing wrong here?