Update:

The solution, for now, which completely worked, was changing "SESSION_DRIVER=file" to "SESSION_DRIVER=cookie" in the .env file.

@dragonberr

be aware, session driver cookie has restrictions on the size of the session. If you have complex forms, you may not be able to store all the previous form data when there is a validation error. I think the max cookie session is 4k

Any other thoughts? The problem seems to be occurring with macs only.

From this: https://www.danielord.co.uk/how-to-set-file-permissions-for-laravel-5-on-mac-osx

the sudo chgrp -R _www storage bootstrap/cache is not working

I thought the problem was with "new users." Any actual solutions/thoughts from anyone?