Product and version:
FileMaker Pro 14.0.4/14.0.2 (Pro and Advanced)
Didn't check older versions but we think in FM13 there was no problem, because we created the reports in FM13 and had no response from users about the problem
OS and version:
Win7 enterprise and OS X 10.10.5 (didn't test other versions)
Empty portals in reports create errors when saved as PDF.
Acrobat Reader (Win and OS X) tells you there are errors in the PDF you should contact the creator of the pdf.
Preview.app on OS X open the same pdf without errors.
How to replicate
Create reports containing portals.
When the portals are empty (no related records) the error is occurs
create a "Hide object when" rule to hide the portal when there are no related records