# eBook Add-on

**URL:** <https://discuss.write.as/t/ebook-add-on/1271>\
**Category:** Labs\
**Created:** [April 15, 2020, 6:14pm UTC](https://discuss.write.as/t/ebook-add-on/1271 "2020-04-15T18:14:27Z")\
**Posts on this page:** 1\
**Showing post:** 82

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**Author:** ![rhubarb](https://discuss.write.as/user_avatar/discuss.write.as/rhubarb/32/964_2.png) [@rhubarb](https://discuss.write.as/u/rhubarb)\
**Post date:** [August 19, 2023, 4:08pm UTC](https://discuss.write.as/t/ebook-add-on/1271/82 "2023-08-19T16:08:04Z")

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Are you still working on epub export, @matt ?

I found some bugs, that might benefit from your attention. 🪳 In order to reproduce them, download [https://write.as/blog/tag:Updates.epub](https://write.as/blog/tag:Updates.epub) and validate with [EPUBCheck](https://www.w3.org/publishing/epubcheck/).

On my machine it resulted in 41 [error messages](https://www.w3.org/publishing/epubcheck/docs/messages/).

Duplicate elements:

- 3x `RSC-016 Fatal Error while parsing file: Attribute "id" was already specified for element "h2".`

Forbidden elements:

- 1x `CSS-001 The "unicode-bidi" property must not be included in an EPUB Style Sheet`

Missing elements:

- 1x `OPF-053 Date value "" does not follow recommended syntax as per http://www.w3.org/TR/NOTE-datetime:zero-length string.`
- 1x `RSC-005 Error while parsing file: character content of element "dc:date" invalid; must be a string with length at least 1 (actual length was 0)`
- 1x `RSC-005 Error while parsing file: Element "title" must not be empty.`

Remote resources not properly referenced or declared:

- 5x `RSC-006 Remote resource reference is not allowed in this context; resource […] must be located in the EPUB container.`
- 4x `OPF-014 The property "remote-resources" should be declared in the OPF file.`

Broken links:

- 18x `RSC-007 Referenced resource […] could not be found in the EPUB.`
- 7x `RSC-026 URL […] leaks outside the container (it is not a valid-relative-ocf-URL-with-fragment string)`

From my own experiments with [pandoc](https://pandoc.org) I’ve learned that creating a properly formatted epub has its unique challenges. It might sound trivial, but an epub is not a website. It is a self-contained entity with a peculiar structure and wrapping.

Hope this helps.

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