Octopress Build Failed UTF-8 Issue

The other day I went to write a blog post but when doing the usual rake generate I got an error saying Build Failed.

Somewhere in the errors logged it mentioned the atom.xml file and Invalid UTF-8.

I checked over the new post I was adding and everything looked ok, no odd characters in there that I could see that would cause an error. I then removed the post from the source/_posts folder and reran rake generate and it worked again.

I then added the post back in, but took out the contents, again it worked, so began adding in the content a paragraph at a time. Eventually I found the cultprit. I'd copied and pasted a URL in from the web and 'somehow' this was breaking it.

I deleted the URL that I'd copied in and wrote it out which fixed the issue.

Weird one, but hopefully it will help someone out there.