I'm trying to convert a Czech language ePub to KFX (have tried a few of them), and am getting 'Internal Error'. Indeed Kindle Previewer (3.65.0) gives same error, without further elaboration, directs me to KPR Help menu to Send Feedback. I've done this, but wondered if you have any idea what the problem might be.
In meantime, MOBI convert works fine.
I downloaded these from pocketbook-int.com:
https://support.pocketbook-int.com/c...ks/u/Czech.zip
Russian language books from the same site convert fine FWIW.
Thank you