EPUB validation error – missing image file in Calibre

Luxfort · 11-04-2026, 12:20 PM

Hello,

I have an EPUB book that I am trying to validate, but I cannot resolve a validation error.

The validator reports a missing image resource:

media/file38.png

I have checked the EPUB in Calibre and tried searching the files, but I have not been able to locate the reference that causes this error.

The book contains an About the Author section with an author photograph. I have checked the image files, but I am still unsure where the incorrect reference is located.

Could someone please explain how I can find the reference to this missing image and correct the EPUB?

I am using Calibre on Windows.

Thank you for your help!

theducks · 11-04-2026, 07:17 PM

Images can be in the CSS (they are usually Backgrounds).
Didn't the debug message say (right side) where it was called from?

JSWolf · 11-04-2026, 07:21 PM

Usually images in CSS are for section breaks.

DNSB · 11-04-2026, 07:24 PM

They can also be used for background images. In one memorable ePub, the cover image was linked in the CSS as a background image with no foreground text (memorable as in who created this piece of crap).

JSWolf · 11-04-2026, 07:26 PM

Quote:

Originally Posted by DNSB

They can also be used for background images. In one memorable ePub, the cover image was linked in the CSS as a background image with no foreground text (memorable as in who created this piece of crap).

Who created that crap?

DNSB · 11-04-2026, 07:52 PM

I actually don't know. It was a selfpubbed book and the only credit in the copyright was Formatting by Greenman. No link or any other information.

JSWolf · Yesterday, 10:27 AM

Quote:

Originally Posted by DNSB

I actually don't know. It was a selfpubbed book and the only credit in the copyright was Formatting by Greenman. No link or any other information.

Oh well. Obviously this Greenman doesn't know how to properly make an ePub.

DNSB · Yesterday, 04:00 PM

Strictly speaking, it was a properly made ePub. At the time I ran into it, epubcheck had no issues other than the cover image not been marked as the cover image. OTOH several ereaders would not correctly display the cover page.

From the stacked divs that increased with each chapter, I did wonder if they were related to the company used by Baen (Pages by Joy Freeman) whose workflow, at one time, added a new div for every html file. One example was Ben Bova's Mars Inc. where the last chapter started with 87 stacked divs. This was what led to my first saved search in Sigil when that feature was added.

JSWolf · Yesterday, 04:05 PM

Quote:

Originally Posted by DNSB

Strictly speaking, it was a properly made ePub. At the time I ran into it, epubcheck had no issues other than the cover image not been marked as the cover image. OTOH several ereaders would not correctly display the cover page.

From the stacked divs that increased with each chapter, I did wonder if they were related to the company used by Baen (Pages by Joy Freeman) whose workflow, at one time, added a new div for every html file. One example was Ben Bova's Mars Inc. where the last chapter started with 87 stacked divs. This was what led to my first saved search in Sigil when that feature was added.

I can easily see where some programs would not like background images. I don't like it when section break graphics are used in CSS. I don't like when any images are used in CSS.

I've only seen Baen books make using a calibre conversion. But 87 divs is beyond silly. When did Baen drop that company?

theducks · Today, 10:50 AM

Quote:

Originally Posted by DNSB

Strictly speaking, it was a properly made ePub. At the time I ran into it, epubcheck had no issues other than the cover image not been marked as the cover image. OTOH several ereaders would not correctly display the cover page.

From the stacked divs that increased with each chapter, I did wonder if they were related to the company used by Baen (Pages by Joy Freeman) whose workflow, at one time, added a new div for every html file. One example was Ben Bova's Mars Inc. where the last chapter started with 87 stacked divs. This was what led to my first saved search in Sigil when that feature was added.

I even have a saved search 'BaenDeDiv' I ran against all files multiple times (usually the number of files in the epub -2) until the changed counter gets to 0. I think this started after Arnold (Webscription era).

DNSB · Today, 02:26 PM

Quote:

Originally Posted by theducks

I even have a saved search 'BaenDeDiv' I ran against all files multiple times (usually the number of files in the epub -2) until the changed counter gets to 0. I think this started after Arnold (Webscription era).

My saved search was handy since it let the computer do the scut work just the way it is intended to.

11-04-2026, 12:20 PM	#1
Luxfort Junior Member Posts: 1 Karma: 10 Join Date: Nov 2026 Device: none	EPUB validation error – missing image file in Calibre Hello, I have an EPUB book that I am trying to validate, but I cannot resolve a validation error. The validator reports a missing image resource: media/file38.png I have checked the EPUB in Calibre and tried searching the files, but I have not been able to locate the reference that causes this error. The book contains an About the Author section with an author photograph. I have checked the image files, but I am still unsure where the incorrect reference is located. Could someone please explain how I can find the reference to this missing image and correct the EPUB? I am using Calibre on Windows. Thank you for your help!

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11-04-2026, 07:17 PM	#2
theducks Well trained by Cats Posts: 32,053 Karma: 65709392 Join Date: Aug 2009 Location: The Central Coast of California Device: Kobo Libra2,Kobo Aura2v1, K4NT(Fixed: New Bat.), Galaxy Tab A	Images can be in the CSS (they are usually Backgrounds). Didn't the debug message say (right side) where it was called from?

11-04-2026, 07:21 PM	#3
JSWolf Resident Curmudgeon Posts: 85,601 Karma: 154365185 Join Date: Nov 2006 Location: Roslindale, Massachusetts Device: Kobo Libra 2, Kobo Aura H2O, PRS-650, PRS-T1, nook STR, PW3	Usually images in CSS are for section breaks.

11-04-2026, 07:24 PM	#4
DNSB Bibliophagist Posts: 55,749 Karma: 182800000 Join Date: Jul 2010 Location: Vancouver Device: Kobo Sage, Libra Colour, Lenovo M8 FHD, Paperwhite 4, Tolino epos	They can also be used for background images. In one memorable ePub, the cover image was linked in the CSS as a background image with no foreground text (memorable as in who created this piece of crap).

11-04-2026, 07:52 PM	#6
DNSB Bibliophagist Posts: 55,749 Karma: 182800000 Join Date: Jul 2010 Location: Vancouver Device: Kobo Sage, Libra Colour, Lenovo M8 FHD, Paperwhite 4, Tolino epos	I actually don't know. It was a selfpubbed book and the only credit in the copyright was Formatting by Greenman. No link or any other information.

Yesterday, 04:00 PM	#8
DNSB Bibliophagist Posts: 55,749 Karma: 182800000 Join Date: Jul 2010 Location: Vancouver Device: Kobo Sage, Libra Colour, Lenovo M8 FHD, Paperwhite 4, Tolino epos	Strictly speaking, it was a properly made ePub. At the time I ran into it, epubcheck had no issues other than the cover image not been marked as the cover image. OTOH several ereaders would not correctly display the cover page. From the stacked divs that increased with each chapter, I did wonder if they were related to the company used by Baen (Pages by Joy Freeman) whose workflow, at one time, added a new div for every html file. One example was Ben Bova's Mars Inc. where the last chapter started with 87 stacked divs. This was what led to my first saved search in Sigil when that feature was added.