Been looking at past discussions and nothing I have tried seems to work. Suggestions would be great. Tried uploading as a book and that did not work.
You could just have one graphic (or font) causing the problem.
Try exporting the first half of the file as PDF and see if it succeeds. Try exporting the second half. If one half works, you can divide the one which failed into two parts, and try each half.
Eventually, you can figure out which page is causing the failure. Then you can eliminate graphics on that page.
If it's not a graphic, it could be a corrupted font. Try replacing a font.
Thanks Steve, it was an issue with a graphic - just not sure what the issue was. Could it be the image size was too big?
Open the graphic in Photoshop or Illustrator (depending on whether raster or vector) and re-save, perhaps in .psd or .ai format.