I posted about this a few years ago but this problem remains unfixed.
I regularly make large "Blurb Photo Book"s in the LR Book Module that bump up against the 440 page limit using standard paper. I also have really lousy internet. I sometimes have to print a "PDF" book to a thumbdrive to upload at a different location with faster internet. This works well.
The problem occurs when I want to switch back to a "Blurb Photo Book" from "PDF" in the Book Module. I get the following error message:
Clearly this is a serious problem for me and one I dont dare try to experiment with to work around. I believe it would not be difficult to set the Blurb Photo Book paper to "standard" paper to avoid this problem.