Created a new book with FrameMaker 2020. Added TOC. Accidently placed it first, before the cover and frontmatter and PDF creates fine. When I move it to proper location, I get a 16044 error and FrameMaker crash. Notice that TOC file icon is brown while all other file icons for book files are white. Could this be related to the problem?
Rebooking after moving TOC into correct location seems to have allowed PDF to create without error. Interesting that when I chose the correct location when creating the PDF it would not work to make the PDF. Thanks for this solution.