WordPress very recently released the much recommended security upgrade WordPress 2.0.6 and it seems a bug was missed that is causing some bloggers to have issues with feedburner feeds. The bug affects the serving of 304 Not Modified feeds and is somehow related to the Server 500 error issue of WordPress 2.0.5.
Mark Jaquith, a a Contributing Developer for WordPress suggests
“My non-Automattic-sanctioned suggestion is for you to download the modified functions.php file here and use that to hold you over until a new version is released. Please do not stay on 2.0.5 because of this issue. 2.0.6 contains several security fixes that you don’t want to miss.”
The issue is affecting some RSS users and only certain servers, and only when the feed attempts to return a 304 Not Modified header. So FeedBurner may fetch it once and miss it the next time. I think WordPress 2.0.7 may be out soon…
Update: Mark updates us that Apache running mod_php is the only affected setup. CGI/FastCGI setups are unaffected, and Lightspeed is unaffected.
Update: Mark comments on Lorelle’s blog that they need need more WP release candidate testers.