EPUBCheck error
OPF-054: Invalid Date Value
This error means a date in the OPF package metadata does not use an accepted W3C/ISO-style format.
Example report
OPF-054: Date value "2021-09-09 16:00:00+00:00"
is not valid as per http://www.w3.org/TR/NOTE-datetime.
OEBPS/content.opf:10:69What is invalid
The value uses a space between the date and time. The metadata parser expects a standards-based date or date-time representation.
Invalid: 2021-09-09 16:00:00+00:00
Valid date-time: 2021-09-09T16:00:00Z
Valid date only: 2021-09-09How to fix it
- Open the OPF file named in the report, such as
OEBPS/content.opf. - Go to the reported metadata line and identify the date property.
- Use a complete date-time such as
2021-09-09T16:00:00Zwhen the time matters, or2021-09-09when a date-only value is appropriate. - Save the package document and revalidate the complete EPUB.
Do not change unrelated publication dates just to make the report disappear. Preserve the intended date and precision while correcting its syntax.
After the repair
A passing EPUBCheck result confirms specification-level validity, but it does not guarantee acceptance by Amazon KDP or another retailer.