Internal Server Error with Quest Theme

I recently upgraded the Quest Theme to 1.3.0. I’m running on GoDaddy with WordPress 4.3.1. When I access the site as a normal user the pages display properly. But when I try to login as an administrator it gives me an Internal Server Error 500. I can delete the last section of the URL to return it to the base site URL and hit enter, it takes me back to the homepage and it looks like I’m logged in. But if I try to do anything requiring admin authority, like access the dashboard, I get the 500 error. This just started with the theme update to 1.3.0.
Barry