When I open an eBook the error message 'InternalError: allocation size overflow' or 'Failed to encode base64 data!' is displayed
Unfortunately the ebook you are trying to open is too large for the EPUBReader Firefox add-on.
When I open an eBook, I just see the cover page but can't navigate to the next page
In all known cases this problem occurs if you also use the Tor-Button-Add-on. To solve the problem, please do the following:
  • Open the eBook in EPUBReader and open the preferences dialog via the gear symbol at the bottom left.
  • Change to the "Miscellaneous" tab and check the option "Javascript enabled". Close the dialog with "Ok".
  • Restart Firefox and open the eBook again. If the problem still occurs, please contact me here.
One hint: for security reasons EPUBReader disables as default Javascript which could be included in the ePub-files. By this change you enabled Javascript, so you should in this case be cautious opening ePub-files from unknown sources.
When I try to install the addon, I get the error message "Not a valid install package". What's the problem?
The file is valid, the problem is caused by a Firefox bug. Here is the workaround: Download the addon first (right click, "save as") and save it to your desktop or somewhere else. After the download is complete, drag the downloaded .xpi file icon from the desktop (or other location) and drop it onto an open Firefox "Add-ons" window.
Can I read ePub-files protected by DRM?
Unfortunately not. In this case you have to use an ePub-reader which supports DRM, e.g. Adobe Digital Editions.
Many ePub-files from Archive.org are corrupted. What's the reason?
Because Archive.org is often very slow, ePub-files are sometimes not downloaded completely. This results in the error message, that the file is corrupted. Just try it several times until you succeed :).
Can I read ePub-files which are already downloaded to my PC?
Yes. Select the Firefox menu "File/File open" and select the ePub-file you want to read or just drag the file on the Firefox window.
Can I page through a long ePub text?
Yes. Use the spacebar on your keyboard for paging down and shift-spacebar for paging up. Alternatively you can use the page-up/-down keys on your keyboard.
Are there any keyboard shortcuts?
Reading style "Book"
←→Pagewise scrolling
Reading style "Website"
↓↑Linewise scrolling
Page up
Page down
Pagewise scrolling
←→Chapterwise scrolling
COpen the ePub-Catalog
SSave a copy of the ePub
DSet a bookmark
+/-Increase/decrease font-size
DelHide/Show the Table of Contents
F11Fullscreen on/off
Can I hide the toolbar?
Yes. Make a right click over the toolbar and uncheck "Always show toolbar". You can show the toolbar by moving the mouse over the bottom of the window.
Where can I find a list with all my ePub-Files?
You can reach this list in three different ways:
  • Select the Firefox menu "Tools/ePub-Catalog".
  • EPUBReader has added a bookmark to the end of your bookmarklist.
  • If you read an ePub-file with EPUBReader, you'll find a button at the bottom with which you can open the list.
  • You can add a button to the Firefox toolbar. For a description see below.
Can I use a button to open the ePub-Catalog?
Yes, you can add a button to the Firefox toolbar. Go to the Firefox menu "View/Toolbars" and select "Customize". Search for the EPUBReader button and drag it to the desired place in the toolbar.

Your question not answered? Please check the manual or send me an email.