Sometimes, even our RSS feed blog is valid, but when you check on feed validator likeFeed validator, you receive the following message: "This feed is valid, but interoperability with the widest range of feed readers could be improved by implementing the following recommendations." or like this one How to fix it?? 1. Go to Feedburner 2. Choose your feed 3. Click Optimize 4. Activate Convert Format Burner and Summary Burner 5. Done Please re-check now. Note : - tested with my RSS feed (Blogger blog) - This is for RSS feed from Feedburner. I dont know it will work or not for other RSS feed services