upload of a photo album in iPhoto for printing service fails > iPhoto quits unexpected? What to do?

Are you uploading to Apple's printing service? Do you get any sort of error message when it fails? What are you trying to get printed? A book, calendar, card or just individual prints?

What system and iPhoto version are you using?

Are you able to create a preview PDF of the book, calendar or card as described in this Apple document: Preview a print project in Photos, iPhoto, or Aperture to avoid issues - Apple Support

If I try safe mode iPhoto quits unexpected during the photo album assembly phase, so even before uploading. I am really puzzled now…!

So am I. That's usually the reverse of what happens - can't assemble normally but can in Safe Mode. What system and iPhoto versions are you using?

iPhoto 11 has many versions from iPhoto 9.0 to 9.4.3. Which version do you have. Use the About IPhoto ➙ About iPhoto menu option to get the exact version no.

Also do you have Time Machine enabled?

Contact Apple via the appropriate phone number for your country from this Apple document and ask about the status of their Print Products Store availably: Contact Apple for support and service - Apple Support