Generating a book on wikipedia appears to have been broken for awhile.
Generation of the document file has failed. Status: Rendering process died with non zero code: 1 Return to User:DennisDaniels/Books/Medical Laboratory Basics
Originally also included in this task description:
How to set up a code bounty to fix this error?
That discussion was moved to https://www.mediawiki.org/wiki/Talk:How_to_report_a_bug#How_to_pay_for_specific_bugs_to_get_fixed_on_Wikimedia.3F