34 articles in this topic. — Page 4 of 5
Ebook conversions go wrong in predictable ways. Whether a file will not open, a layout collapses, or the output is full of gibberish, the cause is almost always the same handful of issues. This is the field guide to the ten most common ebook format problems and the fix for each — plus how to avoid them in the first place.
Most conversion problems are decided before you click convert. A few minutes of preparation — fixing the source file, picking the right target, and avoiding common mistakes — saves a failed job and a broken output. Use this checklist every time you convert an ebook.
You do not need to pay to read ebooks well. Every major platform has a free, capable reader app, and the right one depends on your device and your format. Here is the practical shortlist of free ebook reader apps for 2026, organized by where you read.
Short answer: yes — every Kindle made in the last decade reads AZW3 (KF8) natively. The nuance is what happens on the handful of very old devices that predate the format, and how you actually get the file onto the reader. This breaks down exactly which models open AZW3, what to expect on older hardware, and the difference between AZW3 and Amazon's newer KFX. For the full format landscape including when to pick AZW3 over MOBI, see our Kindle Formats guide.
Bought an EPUB your Kindle won't open? Convert EPUB to AZW3 free — no sign-up, no upload to Amazon. This guide shows how to get a native Kindle format with full typography control, how AZW3 beats the old MOBI, and when to use it instead of Send to Kindle.
Have an FB2 file that won't open on your Kindle? FB2 — FictionBook — is huge in Russian-language ebook circles but nearly invisible everywhere else. The fix is simple: convert FB2 to EPUB, the open format almost every reader supports. This guide covers what FB2 is, why EPUB wins, and how to get your book onto a Kindle afterward.
Sitting on a pile of old .mobi files that only open on a Kindle? MOBI is Amazon's legacy format, and most non-Kindle readers — Kobo, Apple Books, Google Play Books — won't touch it. Converting MOBI to EPUB frees your books to read anywhere, because EPUB is the open standard nearly every device supports. This guide covers the quick conversion and what actually moves across. New to the format question? Our EPUB vs MOBI explainer covers which to keep as your master file.
MOBI vs AZW3 and AZW3 vs MOBI — the answer depends on your Kindle's year. AZW3 wins for any Kindle from 2015 onward; MOBI only matters for pre-2015 hardware. Get the clear pick — plus a one-click, no-install way to convert either direction without losing your formatting. > BookConv processes your file on our servers and automatically deletes it within 1 hour. Files are encrypted in transit, and no account or software install is required.