With nginx and homebrew installs, you may see the following error if you have installed nginx with homebrew (or otherwise) and are seeing error when you try an upload files using wordpress or otherwise:
nginx/client_body_temp/0000000007" failed (13: Permission denied) where the number of the temp directory may different.
/usr/local/var/run/nginx the folders may have been set with restrictive users or permissions. Cd into that folder with
cd /usr/local/var/run/nginx and run
sudo chown -R <your_admin_user>:admin client_body_temp/ to allow the right processes to be able to upload the files.