I found this to be a total pain to figure out how to fix, but once done, the solution is actually very simple.
Most people doing Sharepoint development will be doing so in a proper networked environment (setup by a proper network admin). In which case this article is unlikely to apply to you and this article, can probably point you in the right direction (hint: you need to set your web.config proxy settings).
I am running a Sharepoint development environment at my house, using VMWare, with a minimal win2k3 setup. I’m not a server admin and I’m conscious hits to performance so the environment is very lightweight. No Domain Controller, no Active Directory. I’m a developer not a sysadmin.
Unfortunately, Sharepoint cares not for my developing ways and when I tried adding an RSS webpart to a Sharepoint page got the following on-screen error:
An unexpected error occured processing your request. Check the logs for details and correct the problem.
Crapola. First I thought dodgy rss.
Then I thought, the IIS account doesn’t have web access.
So then I looked at the million and one “Sharepoint rss proxy” articles on Google to no avail. They all want you to make changes to the defaultProxy entry in your Sharepoint’s web.config.
For some reason, if you don’t have a proxy setup, Sharepoint throws it’s toys out the pram and won’t work. It won’t even try to make a network call (I checked using WireShark). Even when I tried to tell the defaultProxy entry to bypass all addresses, it ignored me.
Setup your own proxy. It’s actually very simple (trust me I hate server admin stuff)
Also important is to make sure you use a proper RSSViewer part instead of a RSSAggregatorWebPart (added manually). The only difference I can see is in the configuration xml, but the latter continued to break even after my changes.
Hopefully this doesn’t up some insane hole in my firewall.
Hope that helps.