Hi NB and Old Toad,
Thank you for your updates and advices.
NB, please let me know how it went.
Toad, it looks like your kind advice seem to be working for some others, but my home directory does not look like the image you have given. I am the only user on my computer and there is no separate Library under User directory and I could locate neither of the files that you adviced to delete.
I also lost the older version of iPhoto App (my backup file on the time machine was erased due to not enough memory -- I copied older version of iPhoto library and I guess that took too much memory), so I don't know how to revert to the previous version of iPhoto at this point.
I just upgraded my spouse's iPhoto without any issue. The photo library of my spoous's computer only had 2000 photos.
From what I am reading, I have a feeling that only those of us who has 15000 plus photos are suffering this issues. So, if it is just a size issue, I would think there would be an easy solution. I wonder why Apple won't do something about it instead of letting the customers going through this trouble half-blinded.
The very reason I converted to Apple from Microsoft was to avoid this type of technical issues and the frustration of not getting any help from the tech supports. ðŸ˜