This error can occur if for some reason you have been issued a new passphrase/reading key since you originally downloaded and opened the book. Please re-enter your new passphrase/reading key from your eBooks.com account and your should regain access to the ebook.

If you are a Linux user, if you installed Thorium Reader using your Linux distribution's Package Manager this could be the cause of the issue. Users on NixOS, Arch Linux, and Ubuntu have all reported this issue. Please see this help article for more information.

Please try installing the latest Thorium Reader AppImage or Debian Package directly from the developer's website here: https://www.thoriumreader.com/en/download/

If you are a PocketBook ereader user, and you are receiving this error, please try updating your firmware. Please see this help article for more information.

If this doesn't resolve the issue there may be a temporary issue with the issuing of the reading keys on the eBooks.com website. Please complete our support form to submit a ticket to our customer support. Please be sure to mention the title of the ebook that is having the issue, and attach a screenshot of the error.

In the meantime, while we resolve the issue, you should still be able to access your ebook on Thorium Reader if you import your eBooks.com bookshelf as a catalog using an OPDS feed. The reason why this will still work is the reading key is embedded directly in the OPDS feed. If you haven't already linked your eBooks.com bookshelf as a catalog in Thorium Reader, instructions on how to do so can be found here.