epub conversion adding extra blank pages to ends of chapters

[SueCampbell54]

I can't figure out why this is happening. Another user posted about it in 2016, and the post was moved to the "epub forum" and was never answered. I have known of the (theoretical) existance of this forum, but seems like something changed on the website and we can't actually search for anything in that "forum" or post anything directly to it—even if we add the epub subject tag. But trying anyway.

The file is currently built in CC2018 and I have not really run into this before. The chapters are in a Book file. There is no overset text, nor extra returns or page breaks at the ends of the file. All text and objects are in a single thread in the documents.

When previewing the epub in iBooks there seems to be anywhere for 5 to 16 or so added blanks. looking at the HTML in the unzipped files these are divs with a uniquely numbered image container and a class, within a Basic Text Fram class. Like so:

<div class="_idGenObjectLayout-3">
<div id="_idContainer287" class="Basic-Text-Frame">
</div>
</div>
<div class="_idGenObjectLayout-3">
<div id="_idContainer288" class="Basic-Text-Frame">
</div>
</div>

I don't have any blank boxes in the files that I can find. 

Has anyone else figured out why the extra pages and how to avoid that?

I can removed them in the HTML code, but I would surely prefer not to have to. There ARE background colred pages in the document on other hidden layers (used in the print version) but these shoudn't be exporting at all. Seem's like it would be many more pages ifo that were the case.

Two perhaps related questions: 

1. What is the corrct choice for exporting a book with images to include "classes" or not to include. The default is to include and I've always done that. 

2. Why does an epub exported from a book file with multiple separate ID chapter files create another CSS for each chapter? These are mostly full of idGenObjectAttributes, but why couldn't those be all in one CSS? I believe they are needed for calling out the sizes of objects when they are are all different—I've selected Preserve Appearance and Relative to Text Flow for most images. This is a complex reflowable ebook and writing a single CSS myself would be impossible for me. But all these CSS docs are pretty unwieldly.

[James Gifford—NitroPress]

Funny, I am, right this moment, working on some deep technical details of exactly this subject (page breaks and subsequent page-top spacing)!

What is the last paragraph before the new chapter page? Does it have any odd settings, or a significant amount of space below?

Do you have Split EPUB defined for the Chapter heading style?

Oh, and — what EPUB viewer are you using?

[Sarayu]

Thank you very much, James! I really appreciate your help. Here are the
answers to your questions. I was wondering.since it's only one blank page, I
could probably just erase the html code for that one page in Calibre, though
I don't know code well enough to know what to cut and what not. Here are the
questions:

What is the last paragraph before the new chapter page? Does it have any odd
settings, or a significant amount of space below?

It doesn't have any unusual settings, though it does have a lot of space
after the last lines (most of a page). But I tried cutting out the last few
paragraphs just to see if that was the problem, and I still got a blank
page.

Do you have Split EPUB defined for the Chapter heading style?

Yes, I do have split epub checked in the chapter no. style.

[James Gifford—NitroPress]

No, you shouldn't have to edit the EPUB and, while it was once a thing, it's a poor practice now.

Check that last paragraph and make sure it has no space-below defined, even as an override. (Look closely at everything on those two pages for any kind of formatting override.) Double-check both text frames to make sure no space or other wonky settings have been added.

And remember that if you 'Split EPUB,' you have to either specify the split paragraph style, or tell it to use the paragraphs defined for splitting. (If you're not aware of it, the hamburger menu on Paragraph Styles has an option to review and set all export settings in one list... check that for any anomalies as well.)

This is a simple problem. We just have to find that simple answer. 🙂

[Sarayu]

Thank you, James, i really appreciate your help. But do you think it's significant that when i removed the last paragraphs on the preceding page, nothing changed; but when i removed the chapter number, then the problem didn't occur. So it seems (to my uneducated eye) that the paragraph style on "Chapter One" is the problem, but curiously the same paragraph style was used for all other chapters without a problem? Anyway, i will go through it as you suggested, as that sounds like really good advice.

[James Gifford—NitroPress]

It's hard to be precise about things from exchanging descriptions — I'd have to see the file to be sure. It could be a genuine bug of some kind, or just some detail that's being overlooked in my questions and your descriptions. I can't think of anything that would cause the blank page except Keep/break options, and space/padding where it doesn't belong. If the chapter number isn't causing an extra break anywhere else... that's really odd.

Try creating an alternate chapter number style (just for #1) that does not have break before defined (Keep: Next Page or the equivalent), and don't set that paragraph style to split the EPUB.