Export in EPUB (Reflowable) Issue

Okay, there's a lot of details to this and very few tutorials cover them broadly enough. (Many, even good, up-to-date ones, are "do A, now do B, now do C"... and each of those steps is an entire process that must be understood and mastered in itself unless you are lucky enough to have it work on a first simple pass. They give you no tools for dealing with flaws on each of these steps.)

I'd agree that reflowable is greatly preferable to fixed layout, especially for simple flowing text such as your novel (or equivalents like narrative nonfiction). There's no reason to preserve page structure unless it involves substantial visual content (such as 'art books,' graphic novels, complex how-to books, etc.)

But right off the bat it looks as if you are trying (too hard) to include all print-layout features and visuals in the EPUB. They are different mediums; they need to be regarded differently. Trying to emulate print page layout is contrary to what reflowable e-books are all about, especially as you have no control over the device, screen size, text size and other settings of either the reader app or the human reader's preferences. You need to provide a clean 'liquid' layout that fits everyone's end use.

So, first, I am not sure what's causing the the "non rectangular object" error, but it's likely something that doesn't belong in an e-book, some nonsquare graphic or text frame that does some function in the print layout. You will need to remove it, or null it out, to get a successful export.

Second, you are specifying and embedding fonts. This can be done. It (too) often is done. But IMVHO, it's contrary to the e-book medium, in allowing end readers to choose optimum fonts for their device and preferences, and it adds piles of finicky headache to the technical process, and will always cause some problems for some readers because of the lack of standardization.

So without seeing anything further, I'd suggest the following changes to your EPUB export version:

• Uncheck "Embed fonts" in the export menu.
• Be sure you're using EPUB 3.0 for this export. V2.xx is long obsolete.
• Make sure your content is one continuous text flow, start to finish, with no separate text boxes or flows. Reflowable EPUB wants one flow, and nothing else.
• If you have any graphics or styled text boxes, they must be anchored to the immediately prior text. Objects just stuck on a page either will not export, or will "fall to the bottom" of the document.
• Wherever you've used a manipulated frame or graphic object, either delete it for EPUB export (in a completely separate EPUB source doc, or by using conditional text, or, advanced mode, add a 'display: none' directive in CSS) or make it a simpler, rectangular object for a clean export.

That should get you to a successful first export, even if there are still details to tweak. Further questions welcome.