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Validating and Testing Your eBooks

  • Updated

Like the finer things in life, eBooks don’t look as good as they often do without a lot of testing and loving attention to detail.

Whether you use InDesign or opt for KWL’s conversion tool, chances are, the ePub you generate will not be error-free. You’re likely going to need to do some tweaking and troubleshooting, and even if your ePub file seems to have generated perfectly, you’re still going to have to test it on an actual eReading device or app.

To learn more about validation errors and eBook testing, navigate through the page below:

What are Validation Errors and Why am I Seeing Them?

Every book published through KWL, no matter which format it was originally uploaded in, will be run through something called ePub validation​.EPub validation checks books for technical and structural issues that can affect the way your book functions and looks. Critical validation errors mean that your book has major technical flaws and is unreadable. Non-critical errors are usually small technical inconsistencies that will not affect how your book appears to your readers.

When you’re getting ready to hit publish on your book, the KWL Dashboard will tell you if your ePub has validation errors, and what they are​:

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If the errors you're seeing are non-critical errors, you can publish your book as-is. However, we do recommend that you test your book on a Kobo eReader or app to make sure that there are no formatting issues. If they're critical errors, they will need to be fixed before you can publish your book on Kobo. Please note that your book will not be made available for sale on OverDrive until all validation errors are resolved, even non-critical ones, as OverDrive is not able to accept any ePub files with validation errors.

To find out more about these errors, download your ePub file and run it through a validator. You can use any ePub validator; we recommend the free pagina EPUB validator. Please ensure your program is updated to the latest version. The tool will generate a list of any errors found, giving you the exact location of the errors so you can easily fix them. 

Here’s what a typical error list may look like:

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If you initially uploaded your eBook as a Word doc, continue to the section on Word doc-specific issues below. If you uploaded an ePub, skip past this to How to Open an ePub File.

How to Troubleshoot Validation Errors in Word Docs

Our conversion tool is a great option to easily convert your Word doc into an ePub. However, as our conversion tool is free, it isn't perfect, and occasionally introduces validation errors. The good news is these validation errors are generally non-critical errors, which means they likely won’t affect how your book displays, and you’ll still be able to publish your book on Kobo. Just keep in mind that if you want your books to be available on OverDrive, you will have to resolve these validation errors.

Most of the time, these validation errors are caused by incorrect Word formatting. Before doing anything else, check that your book follows our Word doc conversion guidelines. 

If you’re seeing one of the common validation errors listed below, kindly follow our troubleshooting steps. Otherwise, continue through the rest of the instructions outlined on this page or send us an email if you need more help.

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If you’re seeing this validation error, re-save your image as a .png file if it’s currently a .jpg (or vice versa), then re-upload your cover image and Word doc. This validation error won’t affect how the book displays, but if you want to fix it, this is an easy error message to troubleshoot! 

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This error message usually occurs when text has both heading and list formatting applied to it. Sometimes these headings are clearly part of a list (see below left). Sometimes the headings appear normal, but when highlighted, you can see that the list formatting is selected (see below right). To resolve this validation error, remove the list formatting from your headings. If the text is meant to be numbered, you can remove the heading formatting instead. This error message won’t affect how the book displays.

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This validation error will not affect how your book displays. To troubleshoot, you can try hitting “Backspace” and deleting any empty text at the end of the indicated section in Word, though this does not always fix the issue. If you’re comfortable editing your ePub’s HTML, you can easily go into the TOC file and delete the empty <ol></ol> element where indicated by Pagina.

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This error will not affect how your book displays, but it will prevent it from going to OverDrive. To fix, open your Word document, go to File > Options > Save, uncheck "Embed fonts in the file," then save the document and re-upload.

How to Open an ePub File

    • On a Mac, you can download “ePub Zip“, a free and extremely handy utility that unzips and re-zips your ePub files for you.
    • If you’re on Windows, use a free program like 7-Zip to extract the content of the ePub. We recommend making a copy of the original ePub file before this.

How to Resolve Validation Errors

    • Note the error code listed beside each error message.
    • Look up the error code. A good explanation of these oft-mystifying errors can be found here.
    • If you can’t find the error listed on that website, the best solution is often to Google the error message.

How to Zip an ePub File

  • On a Mac, use “ePub Zip” to re-zip your ePub file.
  • On Windows, the free program eCanCrusher makes re-zipping ePub files simple. Once you’ve downloaded the program, simply drag and drop your unzipped ePub onto the eCanCrusher shortcut, and it will save a re-zipped copy of your ePub.

Testing Your Validated ePub

You’ve worked out the kinks, and the ePub validator is coming back with zero errors. What’s next? Testing, testing, and more testing.

The only way to see how your book will appear to your Kobo readers is to view it on your Kobo eReader or on one of Kobo’s apps, whether that’s our Desktop, Android, or IOS app.

Here’s how to sideload content on Kobo's reading platforms:

eReader

  1. Connect the device to your computer via USB.
  2. Find the drive on your computer in Finder or Windows Explorer.
  3. Drag your EPUB onto the device. If your ePub is reflowable, change the file extension to “.kepub.epub”. If your ePub is Fixed-Layout, change the extension to “.fxl.kepub.epub”. 
  4. Disconnect your device. The file will automatically appear in your library.
  5. Sideloaded EPUBs with the ".fxl.kepub.epub" or ".kepub.epub" will disable bookmarking and note keeping. Thumbnails for covers may not display. Otherwise, the reading experience and content display will be identical to how the file would display when loaded through the store. Leaving the extension as ".epub" will enable bookmarking and note keeping, but the formatting may be different from what your readers will see.

Desktop

  1. Open the Kobo Desktop app.
  2. Make sure you have Adobe Digital Editions (ADE) installed. If you do not wish to install ADE you can skip this step by creating a folder named "My Digital Editions" in your "My Documents" folder. On a Mac, the folder must be named "Digital Editions" instead.
  3. Select the My Books tab in Kobo Desktop and press CTRL+Shift+S on Windows or ⌘+SHIFT+S on a Mac. This will display any files in the “My Digital Editions” folder on your computer with the extension .epub
  4. Any sideloaded books can be removed from the My Books tab by right clicking on the book and selecting "Remove Download".

Android

  1. Connect the device to your computer via USB.
  2. Find the drive on your computer in Windows Explorer. If you use a Mac, install and connect to the device using Android File Transfer.
  3. Drag your EPUB onto the device.
  4. Navigate to the Kobo App, then tap the side bar menu icon on the top left (the icon with the three horizontal bars vertically stacked) to bring out the sidebar. Then tap on either 'All' or 'All Items' based on your app version.
  5. Select options (the three dots on the top right) then “Import”.
  6. Once the files appear, confirm that you want to import them. They will display in your library.

iOS

  1. Connect the device to your computer with the iOS cable.
  2. Open iTunes and click the device's icon in the upper-left corner of iTunes.
  3. Select File Sharing from the Settings menu on the left.
  4. Select the Kobo Books app from the Apps box in the iTunes window.
  5. Drag the EPUB to the Kobo Books Documents box in the iTunes window. If drag and drop functionality is not working then select the "Add File..." button and select the EPUB you want to add to the app. The file will then automatically import and display in your library. If it does not appear even after refreshing your library, closing the app and opening it again should cause the sideloaded titles to appear.
  6. (The Kobo iOS app is registered among apps that open EPUB and pdf files. Users can use the standard “open in…” menu from Safari, Dropbox, or any other app that supports it to view their files.)

Windows

  1. Open the Kobo app, navigate to the Library and swipe up from the bottom of the screen.
  2. Select “import”.
  3. Select the files on the device that you want to import. (The Kobo app will scan all the files on your device that it can import. You may not be able to transfer files via USB depending on the specific Windows device and may need to transfer them by OneDrive, Dropbox, email or some other method instead.)
  4. Select “Open” and wait for the files to load into your library.

Quick QA Checklist

  • Does the book open without any noticeable lag or other loading issue?
  • Can you quickly navigate through the book without seeing any odd behaviour?
  • Look for broken character symbols, odd spacing or any other text-related problems.
  • Are any special fonts displaying correctly? More potential problems with fonts here.
  • Test the links on the Contents page (if you have one). Do they go where they’re supposed to?
  • Click the reading device’s menu to bring up the built in Table of Contents that shows chapter listings. Do the chapters appear as they’re meant to? (Some books do not require chapters to appear.)
  • Are all images where they’re supposed to be? Is there any overlapping?
  • If testing on a phone/tablet: rotate the device. Are there off display issues with the text or any images?
  • If testing Fixed Layout eBooks: is everything (text columns, images, charts) positioned where it should be?
  • If testing interactive eBooks: test the interactive elements. Do they respond as they’re meant to?
  • Did you test across at least two platforms (apps or devices)? More below.

Testing on Different Platforms

This is pretty important. Your book may look great on an eReader but less so on the Kobo Android App. This is especially true of Fixed Layout eBooks. If you don’t have a Kobo eReader to test on, our free Desktop app will display your book similarly to a Kobo eReader. Until you’ve tested on at least one eReader (or the desktop app) and one phone/tablet, you run the risk of missing errors.

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