Bug in marking image as the cover with ePub2.

JSWolf · 03-27-2026, 04:21 PM

Then I mark an image as the cover in an ePub2, I get lines like...

This one is in the metadata.
<meta name="cover" content="coverimg"/>

This one is in the guide.
<reference type="cover" href="images/9781984818553_cover.jpg"/>

The line in the guide triggers an error in the latest epubcheck. So it would be a good idea not to add it to the guide so it won't have to be removed. The error is not a valid "OPS Content Document".

kovidgoyal · 03-27-2026, 09:01 PM

Does not replicate for me. Steps I tried:

1) Open an epub2 file in the editor
2) Right click on an image file and markit as the cover
3) There is no entry in the guide pointing to it, as expected.

JSWolf · 03-29-2026, 03:46 PM

Quote:

Originally Posted by kovidgoyal

Does not replicate for me. Steps I tried:

1) Open an epub2 file in the editor
2) Right click on an image file and markit as the cover
3) There is no entry in the guide pointing to it, as expected.

This scrambled eBook shows the issue. Just mark the cover image as the cover and you'll see the error in the guide.

DNSB · 03-29-2026, 06:05 PM

I checked the book. When I marked the file as the cover image, a item was added to guide section of the opf file pointing at the image and the metadata entry was also created.

Karellen · 03-29-2026, 06:17 PM

When you mark the xhtml file as the Cover, then that guide entry is overwritten with the correct entry.

kovidgoyal · 03-29-2026, 11:14 PM

yes if there is no proper html cover marked then the image is used as a fallback.So it will be fine when you mark the html cover.

JSWolf · Yesterday, 08:33 AM

Quote:

Originally Posted by kovidgoyal

yes if there is no proper html cover marked then the image is used as a fallback.So it will be fine when you mark the html cover.

You don't mark the HTML file that displays the cover as the cover. You mark just the cover image as the cover.

Now that I've provided proof that this is a bug, is this going to be fixed?

theducks · Yesterday, 11:02 AM

Quote:

Originally Posted by JSWolf

You don't mark the HTML file that displays the cover as the cover. You mark just the cover image as the cover.

Now that I've provided proof that this is a bug, is this going to be fixed?

You are supposed to mark BOTH as cover.

JSWolf · Yesterday, 02:16 PM

Quote:

Originally Posted by theducks

You are supposed to mark BOTH as cover.

epubcheck does not flag an error when the HTML is not marked as a cover.

DNSB · Yesterday, 03:31 PM

The guide contents are optional and there is no requirement to list the cover file. OTOH, there is a bit of confusion since the specification also says the guide items must have an href attribute referring to an OPS Content Document included in the manifest. This would seem to make adding a direct link to the cover image an error since an image file is not a valid XHTML/HTML/XML document.

kovidgoyal · Yesterday, 10:51 PM

No, it's not going to be fixed. If you care about epubcheck's asinine errors mark an HTML file as the titlepage in addition to an image. If you mark only an image as the cover then calibre will put that in the guide because that actually helps the epub file work as intended with other software.

JSWolf · Today, 05:01 AM

Quote:

Originally Posted by kovidgoyal

No, it's not going to be fixed. If you care about epubcheck's asinine errors mark an HTML file as the titlepage in addition to an image. If you mark only an image as the cover then calibre will put that in the guide because that actually helps the epub file work as intended with other software.

What other software needs this guide entry for the cover image?

kovidgoyal · Today, 05:28 AM

No clue. This behavior has been present for decades. I am not going to be going out there and doing a comprehensive survey of all software to find out which ones still rely on it.

03-27-2026, 04:21 PM	#1
JSWolf Resident Curmudgeon Posts: 82,707 Karma: 151278869 Join Date: Nov 2006 Location: Roslindale, Massachusetts Device: Kobo Libra 2, Kobo Aura H2O, PRS-650, PRS-T1, nook STR, PW3	Bug in marking image as the cover with ePub2. Then I mark an image as the cover in an ePub2, I get lines like... This one is in the metadata. <meta name="cover" content="coverimg"/> This one is in the guide. <reference type="cover" href="images/9781984818553_cover.jpg"/> The line in the guide triggers an error in the latest epubcheck. So it would be a good idea not to add it to the guide so it won't have to be removed. The error is not a valid "OPS Content Document".

03-29-2026, 06:05 PM	#4
DNSB Bibliophagist Posts: 50,951 Karma: 179232776 Join Date: Jul 2010 Location: Vancouver Device: Kobo Sage, Libra Colour, Lenovo M8 FHD, Paperwhite 4, Tolino epos	I checked the book. When I marked the file as the cover image, a item was added to guide section of the opf file pointing at the image and the metadata entry was also created. Attached Thumbnails Last edited by DNSB; 03-29-2026 at 06:11 PM. Reason: removed comment about alternative ePub editor

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03-27-2026, 09:01 PM	#2
kovidgoyal creator of calibre Posts: 46,153 Karma: 29626604 Join Date: Oct 2006 Location: Mumbai, India Device: Various	Does not replicate for me. Steps I tried: 1) Open an epub2 file in the editor 2) Right click on an image file and markit as the cover 3) There is no entry in the guide pointing to it, as expected.

03-29-2026, 06:17 PM	#5
Karellen Wizard Posts: 1,808 Karma: 9501034 Join Date: Sep 2021 Location: Australia Device: Kobo Libra 2	When you mark the xhtml file as the Cover, then that guide entry is overwritten with the correct entry.

03-29-2026, 11:14 PM	#6
kovidgoyal creator of calibre Posts: 46,153 Karma: 29626604 Join Date: Oct 2006 Location: Mumbai, India Device: Various	yes if there is no proper html cover marked then the image is used as a fallback.So it will be fine when you mark the html cover.

Yesterday, 03:31 PM	#10
DNSB Bibliophagist Posts: 50,951 Karma: 179232776 Join Date: Jul 2010 Location: Vancouver Device: Kobo Sage, Libra Colour, Lenovo M8 FHD, Paperwhite 4, Tolino epos	The guide contents are optional and there is no requirement to list the cover file. OTOH, there is a bit of confusion since the specification also says the guide items must have an href attribute referring to an OPS Content Document included in the manifest. This would seem to make adding a direct link to the cover image an error since an image file is not a valid XHTML/HTML/XML document.

Yesterday, 10:51 PM	#11
kovidgoyal creator of calibre Posts: 46,153 Karma: 29626604 Join Date: Oct 2006 Location: Mumbai, India Device: Various	No, it's not going to be fixed. If you care about epubcheck's asinine errors mark an HTML file as the titlepage in addition to an image. If you mark only an image as the cover then calibre will put that in the guide because that actually helps the epub file work as intended with other software.

Today, 05:28 AM	#13
kovidgoyal creator of calibre Posts: 46,153 Karma: 29626604 Join Date: Oct 2006 Location: Mumbai, India Device: Various	No clue. This behavior has been present for decades. I am not going to be going out there and doing a comprehensive survey of all software to find out which ones still rely on it.