Exporting multiple pages as PDF results in corrupt download, but Word export is fine

Exporting multiple pages as PDF results in corrupt download, but Word export is fine

When a user selects all wiki pages for export (a total of about 100 pages, or about 800Kb of data), then clicks the PDF icon to export all pages as PDF, the resulting PDF is corrupt and cannot be opened by Preview or Adobe Reader.

However the same selection can be exported to Word and opened successfully.