From IndesignSecrets. For full details see the article:
InDesign CS5.5 brings many improvements to the creation of EPUB files. A posting hererevealed some of the improvements. However, recently I ran into a bug which occurs when exporting EPUB out of InDesign CS5.5, which does not occur in InDesign CS5. It has been described as a WebKit encoding bug.
I was working on creating two eBooks, and I had started them in InDesign CS5. When InDesign CS5.5 was completed, I happily opened them in the new version because using CS5.5 required a lot less postprocessing of the files. The chapters passed EPUB validation, but when I tried to preview some of them on my iPad (and my iPhone) in Apple’s iBooks eBook reader, I saw this strange message (shown in a screen capture from my iPhone):
WebKit Error Message
