This is an exercise on one of the most common problems i usually encounter when creating ePubs.
When updating ePubs, the process usually goes like this:
1. Open the latest ePub of that series. (just to make sure)
2. Find the last chapter.
3. Download the next chapters either via script or manually (depends on the series, really).
4. Load those next chapters on the ePub.
5. Edit the heck out of it until it passes QA.
Truth be told, if i bypass step 5, then things would go faster.
Anyways, from step 5 to step 6, for EPUB2 versions, there are no extra steps to be done other than generating the TOC (Table of Contents), then saving it.
For EPUB3 versions, there are additional steps that needs to be done, so that the changes can be reflected properly.
The additional steps, aside from updating the TOC, are the following:
5.1 Update Manifest Properties
5.2 Generate NCX from NAV
The manifest file is a special file that can contain information about the files in the ePub. This needs to be updated when you make changes in your epub, especially when you add or remove files.
Basically, just updating the manifest file is already enough for most ebook readers. But it would seem that for other readers, this is not enough. You also need to update the NCX.
The NCX file was an early attempt at creating a way for eBook readers to navigate a document in a way similar to a table of contents. The ePub 3.0+ standards no longer require an ncx file because its successor is the navigation document. Therefore, if you want to your eBook to the widest possible audience, it is a good idea to add an ncx file so you can be backward compatible with other eBook readers. (now you know why i bother with the additional 2nd step. It's addressing the backwards-compatibility of the epub to old ebook readers in your devices and such)
Occasionally, i often get flagged that on some epubs, the updates are not visible, or missing chapters. Previously, i had mistaken that error to be a filename problem inside the epubs. Hence why the filenames inside my epubs are uniform and numerical in order.
Turns out, i was mistaken.
Irregardless of the filename, the problem still persists.
But eventually i've narrowed it down to just a simple failure to update the NCX of the ePub.
See, when i'm updating the ePubs and checked it with my ebook reader (i use Moon+ Reader, btw), the new chapters are displayed correctly. But others are reporting differently.
To make the already long story, short. I just need to update the NCX of the ePub, so that the updates are displayed correctly for others.
end of story.
(and no, this was not purposely done, because Book 14 of the series Battle Through The Heavens, was flagged as having missing chapters by one of our fellow readers. Suffice to say, i forgot to update the NCX for it, and now, it's already fixed)
and i highly recommend Moon Reader! And please do not forget to adjust the settings "use embedded fonts" for my ePubs!