I'm working on my first theme from scratch. So far so good. Locally with XAMPP everything works fine. I uploaded my theme to my FTP Server. Now I get a Whitescreen after publishing/editing a post. I have no plugins except Hello Dolly and a Coming Soon Plugin (which I tested, they work fine with other themes). Also other themes seem to work fine, no problems here. So I assumed it has something to do with my functions.php. So I cleared it entirely since a theme does no necessarily need it. It still does not work. In my debug.log file it says:
Warning: Cannot modify header information - headers already sent by (output started at ../wp-content/themes/inital/functions.php:2) in ../wp-admin/post.php on line 197
Is this the reason it's not working? How can I fix it?
Thanks for any help.
Wordpress Version 4.8.1