Hi Curt. I commiserate. I had an identical error recently. I also worked out it was related to the index. I was working on a clean file – meaning I had had the same error in an earlier edition of the same book (in an earlier version of Indesign) and had decided to start completely afresh with the new edition to eliminate any possible artefacts. But it came up again in the pristine edition and I could not track it down. I finally left the thing there because I found that when I created the reflowable epub and tested the index on a number of different epub readers everything that mattered seemed to be working OK. I also got the number 71, and knowing that you got the same error lets me know it wasn’t anything to with Page 71. Something might not have been working optimally but not that I could find. I actually didn’t do the validation step (which I realise is not recommended. This is partly because I had already taken the book from epub to the latest version of Kindle previewer (the desktop version) to make sure Kindle processes could handle it. It had no problem with the conversion from epub to mobi. This was a complex book with about 50 diagrams images, footnotes, TOC (internal and navigational). I did find another problem related to the index (which may or may not be associated with this page anchor messsage). I found that where I had entries spanning a number of pages only the first ( or was it the last) page entry was live. I found a post purporting to fix this issue (more or less) but it was a complex fix and I left it alone. From memory it only happened with reflowable epubs. Briar