Thank you for the prompt reply. I have just tested the same functionality in 4.0 (build 4.0.1098) and deleted most of the fields in the Feed's data structure(please find the RSS output attached to this reply). However, the error does not reproduce on my side, could it be that you have included some item that has no default URL in your feed? By the way one thing I might have forgotten to mention, is that you need to restart the application for the setting to apply. The best way to isolate this would be if I ask you for a small favor - can you, please, check if the error reproduces if you create a blank project with the same version of Sitefinity project manager? Also, can you just clarify where do you see the author email displayed, as well as the tags (probably a screenshot or temporary login credentials to your site's backend would be useful) since the default RSS output that we're generating did not contain these when checking the Feed page? Thanks in advance.
the Telerik team
Do you want to have your say in the Sitefinity development roadmap? Do you want to know when a feature you requested is added or when a bug fixed? Explore the Telerik Public Issue Tracking
system and vote to affect the priority of the items