I had this problem too. My advice is look in your server error log file. For me, it was that the top directory for the project was not readable. The error log clearly stated this. A simple
sudo chmod 755 <site_top_folder>
fixed it for me.
I had this problem too. My advice is look in your server error log file. For me, it was that the top directory for the project was not readable. The error log clearly stated this. A simple
sudo chmod 755 <site_top_folder>
fixed it for me.