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Format Not Supported / Can't Open File

Barnes & Noble Nook

Severity:

Source: OnlyErrorCodes.com — Every error code. One place.

Nook Format Not Supported — Fix Guide

What Does This Error Mean?

Nook supports EPUB and PDF formats for sideloaded books — it does not natively support MOBI, AZW (Kindle), or CBZ files. To read an unsupported format on your Nook, convert it to EPUB using the free Calibre desktop application.

Affected Models

  • Nook GlowLight 3
  • Nook GlowLight Plus
  • Nook Tablet 7
  • Nook Tablet 10.1

Common Causes

  • File is in MOBI or AZW format (Kindle formats not supported by Nook)
  • File is a CBZ or CBR comic archive — not natively supported
  • EPUB file uses DRM from a non-B&N source (Adobe DRM requires Adobe account setup)
  • File transferred to wrong folder — must go to the My Files/Books directory
  • EPUB file is corrupted or malformed

How to Fix It

  1. Check the file format.

    Nook supports: EPUB (most common), PDF, and B&N purchased content. Nook does not support: MOBI, AZW, AZW3 (Kindle formats), CBZ, CBR, or LIT. Right-click the file on your PC and check the file extension to confirm the format.

  2. Convert the file to EPUB using Calibre.

    Download the free Calibre ebook manager from calibre-ebook.com. Drag your unsupported file into Calibre, right-click it, and choose Convert Books > Convert Individually. Set the output format to EPUB and click OK. Transfer the converted EPUB to your Nook via USB.

  3. Transfer the file to the correct folder.

    When connecting the Nook to a PC via USB, copy sideloaded EPUBs to the My Files > Books folder on the Nook internal storage. Files placed in the root or other folders may not appear in the Nook library.

  4. Set up Adobe Digital Editions for DRM-protected EPUBs.

    Public library books from OverDrive and some publishers use Adobe DRM. To read these on your Nook, install Adobe Digital Editions on your PC, create a free Adobe ID, and authorise both your PC and Nook with the same Adobe ID. Then transfer the EPUB via ADE rather than direct USB copy.

  5. Verify the EPUB file is not corrupted.

    Open the EPUB in the free Calibre viewer on your PC — if Calibre also cannot open it, the file itself is corrupted. Download the file again from the original source. EPUBs downloaded from free ebook sites are sometimes incomplete or malformed.

When to Call a Professional

This is a format compatibility issue, not a device fault. No professional service is needed — use Calibre to convert the file.