Epub can't convert to pdf

The file epub can’t convert to pdf.
Java groupdocs-conversion-21.7.jar
test epub file.zip (2.4 MB)

test epub file.zip (2.39 MB)
epub to pdf error.png (37.0 KB)

@zsnqsl
We have opened the following new ticket(s) in our internal issue tracking system and will deliver their fixes according to the terms mentioned in Free Support Policies.

Issue ID(s): CONVERSIONAPP-600