RSS Error: WP HTTP Error: Couldn’t resolve host

I’ve been working on a blog and wanted to add RSS Feed from another blog using RSS Widget. After entering the feed URL and Title I got following error:

RSS Error: WP HTTP Error: Couldn’t resolve host

I’m sure I’ve seen this issue in the past in another blog but somehow I forgot how did I solved it. I wish I had blogged it after solving.

Any way let’s see what is wrong here. I did some step by step debugging. First I entered feed url of another blog (on different domain) hosted on same server to rule out any server related issue as reported on http://wordpress.org/support/topic/wp-http-error-couldnt-resolve-host.

It worked. So the server was not a problem.

And then the bulb lit ;)

The problem was that I was trying to add feed url from same domain. It seems this RSS widget can’t resolve the feed url from same domain blog.

So let’s say if you have 2 blogs

http://blog1.domain.com and http://blog2.domain.com and if you try to use the feed from one subdomain (let’s say http://blog1.domain.com/feed) to another subdomain (http://blog2.domain.com) then it will not work.

Humm!!! Why?

What about the WPMU based Blogs? That works for sure. You can certainly use the RSS feed url from one blog on WPMU to another blog on same WPMU installation.  To test this theory I tried it on a blog on  Blog Scribble and it worked.

I haven’t found a solution, but I’m assuming that you can’t use the feed from same domain blogs in RSS widget?

What if you use blog’s own feed into RSS Widget ;)

Well it will throw following error in the widegt:

RSS Error: WP HTTP Error: Couldn’t resolve host

I’ll keep posted if I find a solution.