Problem with epub zip files sent via Wireless Device?

I'm seeing problems where some of the epubs sent to CC in my phone from Calibre have (slightly) damaged zip files when they arrive.

(For anyone who didn't know, an epub is a zip file with a bit of standardized structure.)

I say '(slightly)' because some book readers, including Calibre, can still read them.

I noticed the problem from Android app @Voice Aloud Reader reporting "This ebook file appears to be damaged" for some, but not all, of my recent uploads. When I reported it to them with the epub, they pointed out the damaged zip.

I'm using Calibre 4.18 on Windows 10 and Calibre Companion 5.4.4.10 (401) on Android 10(?) on a Samsung Galaxy S10e, connecting as a Wireless Device.

Attached is one of the damaged epubs as copied from the CC dir on the phone and exhibits the following errors. The same book taken from the Calibre dir directly, saved from Calibre, and sent to a Nook from Calibre has no issues.

Errors:


Any help getting this fixed would be appreciated.

Attached Files

cc2 Live Forever - Petrificus Somewhatus.epub (184.4 KB)