I’ve added my own blog to NewsBlur and I get this error fairly regularly. I can reproduce it every time I hit “Parse this RSS/XML feed” in site settings.
Since this is my own website, I’d rather like to know what it is I should be fixing. W3 feed validator says my feed is valid.
I would love to provide more details. In fact, I have the details, but it’s quite a bit of work to move them up to where you can see them. Sometimes the issue isn’t so easy to understand, sometimes it’s just that no RSS feed was found on the website. If it is taking a super-long time, then it’s almost undoubtedly timing out, which happens to an unfortunately high number of feeds (in any given 5 minute period of the day, about 4,500 feeds are fetched, and between 30-40 time out).