xml parsing error xml or text declaration not at start of entity in wordpress feed
Try installing fix-rss-feed plugin.
Also I think you have a space before <?xml version="1.0" encoding="UTF-8"?>. Getting rid of it should do the trick.
fix-rss-feed plugin is outdated. I had the same problem with the RSS feeds, try the solution provided here http://wejn.org/stuff/wejnswpwhitespacefix.php.html it works like charm!
In my opinion, rather than using a plugin, a better solution would be to remove all trailing white space across all PHP files in your theme directory. In a terminal window run:
cd yoursite/wp-content/themes/yourthemethen run
find ./ -name "*.php" -exec sed -i -e '/^\n*$/d' {} \;After that runs, try navigating to yoursite.com/feed