Downloaded books not opening

[Vidyut G K]

I have used Anthologize successfully before, but now there seems to be something wrong (I have shifted servers too since). I create a book, but when I export it, the pdf and rtf won't open, though the filesize indicates that there is content. The html version shows onlly one post. Error messages seem to indicate that the file has problems.

I am on a Nginx server.

Wondering if there are any dependencies I may have missed.