This tutorial is for webmasters who maintain there own website using "Google Webmaster Tool"
I faced this error with this blog(blogger.com) a few days before. Beside my sitemap xmls i saw error and when i click to see the details i saw the following under SiteMap errors and warnings.
And the message says:
URL not allowed
This url is not allowed for a Sitemap at this location.
This error came with blogger!
There is a simple solution for this (Verified and works for blogger)!
Select any one of your sitemap and delete it. Say you deleted the Atom Feed. Now again add the atom feed but as shown below:
atom.xml?redirect=false
You could remove both the feed and replace it with redirect as false but i would suggest to keep at least anyone intact just now to screw up anything. :)
