I'd like to add the list of supported feeds to FAQ 151: Why might a syndicated account not update correctly?. Text copied directly from FAQ 137.
Why might a syndicated account not update correctly?
Out of many possible reasons why a syndicated account isn't updating correctly, the most common is an invalid RSS or Atom feed.
- Invalid RSS or Atom feed: A normal HTML page will not work, because a feed contains RSS or Atom code instead. You can check with a feed validator, which can be found by a search for "feed validator" in your favorite search engine.
- Feed Not Updating: Sometimes the feed will stop updating, even if the site itself is updating.
- Connection Problems: Lack of feed updates can be caused by a problem with the other website, a network problem between the site and LiveJournal, or by the site deliberately blocking LiveJournal. In the first two cases, the problem will normally resolve itself within a few days. In the latter case, this is the right of the external site, and there is nothing that LiveJournal can do to circumvent this.
- Feed File Size: The feed file must be under 150KB in size because LiveJournal does not support larger feeds.
- Recognized Text Encoding: The feed must use a text encoding which LiveJournal recognizes, such as UTF-8. Otherwise, the syndicated account won't update. You will need to speak with the feed owner about changing the feed's encoding.
- Recognized Feed Format: LiveJournal supports RSS versions 0.9, 0.91, and 1.0 and Atom feeds greater than 0.3. While LiveJournal may accept feeds in other formats, they may not work.
- Accurate Dates and Times: If the dates and times reported by the feed are incorrect, LiveJournal may not interpret the feed correctly or update the syndicated account. This applies both to dates and times within the feed's text and http headers.
- <guid> and <link> tags: If the same <guid> tag is used for two items, then LiveJournal will interpret the second as an update to the first and edit the old entry, rather than creating a new one. The same applies to the <link> tag if different links are normally provided for each entry. On the other hand, if a new <link> or <guid> is given to an item in the feed when it is edited, this will cause LiveJournal to post a new version of the entry.
- RSS Extensions: In many cases, feed creators include extra functionality within the feed along with traditional RSS or Atom code. LiveJournal supports the core formats and several frequently used extensions, but may not work with all extensions.