# EPUBCheck OPF-054: Date value … is not valid as per…

Source: https://epublab.com/epubcheck/opf-054/ (updated 2026-11-03)

EPUBCheck OPF-054 is an error message: “Date value "…" is not valid as per http://www.w3.org/TR/NOTE-datetime:….” A date in the metadata is not a valid date.

- Official message (EPUBCheck 5.4.0): Date value "%1$s" is not valid as per http://www.w3.org/TR/NOTE-datetime:%2$s.
- Default severity: Error

## Typical causes

- Impossible dates such as 2020-13-01, or text that is not a date in a date field.

## How to fix it

- Correct the value to a real date in YYYY, YYYY-MM or YYYY-MM-DD form.

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