# EPUBCheck OPF-001: There was an error when parsing the…

Source: https://epublab.com/epubcheck/opf-001/ (updated 2026-11-03)

EPUBCheck OPF-001 is an error message: “There was an error when parsing the EPUB version: ….” EPUBCheck could not read the EPUB version from the package document.

- Official message (EPUBCheck 5.4.0): There was an error when parsing the EPUB version: %1$s.
- Default severity: Error

## Typical causes

- A missing, empty or malformed version attribute on the package element.

## How to fix it

- Set the version attribute on the package element: version="3.0" for EPUB 3 (EPUB 3.3 still uses 3.0) or version="2.0" for EPUB 2.

Message text and severity: EPUBCheck (W3C, BSD-3-Clause). Explanation: EPUBLab.