RichFaces has recently moved into version 4, providing compatibility with JSF 2.0. Pretty cool.
The problem is that it can be a bit confusing when upgrading from version 3, or when following some of the slightly outdated documentation on the site.
If you've dutifully followed the getting started instructions for RichFaces when working with version 4, you probably added these lines to your web.xml file:
And yet you're still getting that horrible filterStart error, aren't you? No problem, my friends. Here's how to fix it:
Delete those lines from your web.xml.
The JSF 2.0 spec handles those configurations already. By adding those lines into your web.xml you're just going to confuse the poor thing.