Boundary first. This is a plain-English error guide. There is no upload form here. If you ask for help, start with the EPUBCheck error log only, not a full manuscript.

EPUBCheck errors explained in plain English

If your EPUB exported from Atticus, Vellum, Draft2Digital, Calibre, Scrivener, InDesign, or another tool fails validation, the first useful step is not panic. The first step is to understand whether the error is a small file-level EPUB issue or a publishing-platform problem.

What this draft covers

These notes explain common EPUBCheck errors in human language: what they mean, why they happen, what you can check yourself, and where a small fix ends.

Common errors

What a small EPUBCheck fix can do

Explain the validation error in plain English.
Fix deterministic file-level EPUB package issues.
Run EPUBCheck again and keep the report.
Tell you when the file is not really an EPUB or when the problem belongs to your export tool or retailer account.

What it cannot promise

An EPUBCheck pass is not the same as final acceptance by KDP, Apple Books, Google Play Books, Draft2Digital, or another retailer. Retailers can still reject a file for content, copyright, metadata, cover, layout, account, or policy reasons.

Lightweight next step

If you want a first-pass triage, send the EPUBCheck error log only. Do not send a full manuscript or platform login. The first answer is simply whether the error looks like a small file-level EPUB fix.

Send the error log only

Reference tool: W3C EPUBCheck.