Explain the problem.

pandoc --from markdown --to epub "file name.md" -o "file name.epub" --toc=true --epub-cover-image="cover image.jpg"

The resultant EPUB has spaces in the cover image file name and the URLs used within the EPUB do not URL-encode these spaces, causing validation errors.

Strangely, when I use an image file with no spaces, which passes validation, the cover image still doesn't appear in Google Play Books. (And yes, I did see that I need to include the image in the metadata as cover-image. That is in-place.)

Pandoc version?

Pandoc 3.5 on Windows 10.