Aperture crashes when opening library

Hardware Environment:

- Macbook Pro Mid-2012 w/240 Gb OWC SSD

- 27" Thunderbolts display

- OWC external Thunderbolt enclosure with one 3 Tb Western Digital hard drive and one 1.5 Tb WD hard drive.

- Macbook and OWC enclosure both connected to Thunderbolt display

Software Environment:

- OS X El Capitan 11.2.4 Beta (15E27e)

- Aperture 3.6

- 190 Gb managed Aperture library consisting of about 37,000 photos stored on the 3 Tb drive

- Smaller managed library on the Macbook's SSD (used while on the road)

Issue description:

About a week ago, Aperture crashed while I was performing a bunch of usual tasks (importing, editing, cataloging). It crashed repeatedly upon each attempt to re-open until I got the warning that repeated crashes indicate a problem (really?) and I should repair the database. I did so; still crashed. I repaired permissions; still crashed. I rebuilt the database; still crashed. As a last resort, I created a new library and tried to perform a restore from the vault that I religiously kept up to date on the 1.5 Tb external drive, but the restore operation locked up the machine about 2/3 of the way through and then, hands off, the Macbook rebooted. I reopened the new file that Aperture was attempting to create during the restore operation. There were a lot of photos that made it over. and a lot that didn't.

At this point I thought that it would be a good idea to 'relocate' those photos that survived the restore, i.e. convert them from 'managed' to 'referenced', so that if I could never get Aperture to run again I'd at least have something left. Aperture crashed partway through the relocation process. I downloaded a trial copy of Capture One Pro 9, and tried importing the Aperture library, but it crashed after about 8000 images. In short, I cannot get at all of my 37,000 photos in Aperture!

Here's the really interesting part: if I run Aperture using my MUCH smaller library on the MacBook's internal SSD, it works fine and is stable. Aperture had been running fine with this library under this beta version of El Capitan for some time before the issue arose. If I import the entire library into Photos, they all come over, but I loose the several books that I have built or are in the process of designing and I loose my catalog structure.

It certainly seems that there is some kind of corruption in the bigger library that the built-in repair tools can't detect or can't fix. Can anyone think of any way to fix this outside of starting over in the Photos app?