Validating RSS-feeds can be quite difficult, espacially if you have a website with user generated content and people use some strange characters in their own language, for example “ä” (ä) . If this HTML-entity is saved like this : “ä” in your database you have  a problem because  XML only has 5 predefined entities.

If your document is read by an XML parser that does not or cannot read external entities, then only the five built-in XML character entities  can safely be used.To get your RSS-feed valid, you need to write a function to encode and decode and I found a nice one here: