You will encounter this error is you try to import your eBooks.com bookshelf as an OPDS feed to FBReader.

We use OAuth to secure our OPDS feeds. Unfortunately this is not yet supported by FBReader. But we have contacted them to request they add support in fute.

In the meantime, you can still read your ebooks in FBReader, but it will involve downloading the lcpl files individually. For more information on how to do that, please see our guide to downloading an ebook to Thorium Reader (the steps are the same).

If you are having technical difficulties at any point please use our troubleshooter, or you can always contact our support team, who will be happy to help.