question for hive-mind viz. Apple error message on valid epub

Hello epub 3 experts,

Our small publishing group is attempting to upload to a distribution org an epub that has passed validation through epubcheck but is being rejected by Apple with this message:

"The provided file has failed validation at Apple. As a result, Apple cannot process any metadata/content updates or activate this content for sale without action on your part. Please validate the ePub and correct any errors or issues detailed below:

ERROR ITMS-9000: The video file(s) in the book must be H.264 and end with a .MP4 or .M4V file extension. More information about video encoding can be found in the Apple Books Asset Guide in the Deliver Your Content module on iTunes Connect. Unsupported file found : video/unapologetically-jackie-h264-360p-2398-stereo-121222-vs6ntw.webm"

The videos provided within the book are .mp4 and .webm formats. I have previously submitted to Apple similar books with embedded video without an issue. Searching for more information on the FLAG ERROR ITMS-9000 doesn’t give me any more enlightenment to the problem.

Anyone have an idea what could be the issue?


ruth tait
https://www.artbyrt.com
O: 613 604 2781