Flightdeck validation error - nonlinear content

Cepheus · 04-18-2023, 11:33 AM

Just wondering if anyone has run into this error message before?

Non-linear content must be reachable, but found no hyperlink to "OEBPS/cover.xhtml".
Look at line 50 in this file: OEBPS/package.opf

We use an XSLT process to generate our ePubs. Line 50 in our package.opf file looks just like all our other ePubs that do validate in Flightdeck

<item id="cover" href="cover.xhtml" media-type="application/xhtml+xml"/>

As Flightdeck does not inform us of how to rectify the issue we are kind of stumped. Has anyone else run across this issue before?

KevinH · 04-18-2023, 11:54 AM

You are including the cover.xhtml file in the OPF spine with linear="no" but the latest epubcheck requires that there be an existing link to any file included in the OPF spine.

The solution depends on epub version.

In epub2, you add the "cover" semantic to that file in the OPF guide thereby creating an external link to it.

In epub3, you add the "cover" semantic to that file in the NAV landmarks, thereby creating an external link to it from another xhtml file (in this case the Nav).

Alternatively, if you have a title page or html toc, you can simply create a normal hyperlink to that cover.xhtml and that should address that issue as well.

Aside: Why do you pay for something that free tools like epubcheck, Sigil, Calibre can provide? What advantage does Flightdeck actually provide? I am curious.

Cepheus · 04-18-2023, 02:14 PM

Thank you for your reply. I don't personally use Flightdeck. The publishing company I work for uploads our ePubs to Firebrand and they use Flightdeck to validate those ePubs. It is a little more in depth than epubcheck and we have no choice but to make sure we pass their validation check.

I'm hoping this validation error is not something we will have to continue with for every ePub we make. It is going to require us to manually edit the files. Validation errors have become an issue lately and the errors are always issues that were not a problem up until the past few months.

We shall see. Thank you again for your reply. You've saved us!

Jellby · 04-18-2023, 02:18 PM

Well, non-linear items in the spine must still be accessible somehow, so you need a link somewhere. I think the error is correctly signalled.

04-18-2023, 11:33 AM	#1
Cepheus Member Posts: 18 Karma: 10 Join Date: Mar 2019 Device: Kindle	Flightdeck validation error - nonlinear content Just wondering if anyone has run into this error message before? Non-linear content must be reachable, but found no hyperlink to "OEBPS/cover.xhtml". Look at line 50 in this file: OEBPS/package.opf We use an XSLT process to generate our ePubs. Line 50 in our package.opf file looks just like all our other ePubs that do validate in Flightdeck <item id="cover" href="cover.xhtml" media-type="application/xhtml+xml"/> As Flightdeck does not inform us of how to rectify the issue we are kind of stumped. Has anyone else run across this issue before?

04-18-2023, 11:54 AM	#2
KevinH Sigil Developer Posts: 7,727 Karma: 5444398 Join Date: Nov 2009 Device: many	You are including the cover.xhtml file in the OPF spine with linear="no" but the latest epubcheck requires that there be an existing link to any file included in the OPF spine. The solution depends on epub version. In epub2, you add the "cover" semantic to that file in the OPF guide thereby creating an external link to it. In epub3, you add the "cover" semantic to that file in the NAV landmarks, thereby creating an external link to it from another xhtml file (in this case the Nav). Alternatively, if you have a title page or html toc, you can simply create a normal hyperlink to that cover.xhtml and that should address that issue as well. Aside: Why do you pay for something that free tools like epubcheck, Sigil, Calibre can provide? What advantage does Flightdeck actually provide? I am curious. Last edited by KevinH; 04-18-2023 at 05:57 PM. Reason: learned to type!

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04-18-2023, 02:14 PM	#3
Cepheus Member Posts: 18 Karma: 10 Join Date: Mar 2019 Device: Kindle	Thank you for your reply. I don't personally use Flightdeck. The publishing company I work for uploads our ePubs to Firebrand and they use Flightdeck to validate those ePubs. It is a little more in depth than epubcheck and we have no choice but to make sure we pass their validation check. I'm hoping this validation error is not something we will have to continue with for every ePub we make. It is going to require us to manually edit the files. Validation errors have become an issue lately and the errors are always issues that were not a problem up until the past few months. We shall see. Thank you again for your reply. You've saved us!

04-18-2023, 02:18 PM	#4
Jellby frumious Bandersnatch Posts: 7,516 Karma: 19000001 Join Date: Jan 2008 Location: Spaniard in Sweden Device: Cybook Orizon, Kobo Aura	Well, non-linear items in the spine must still be accessible somehow, so you need a link somewhere. I think the error is correctly signalled.

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