It seems you have a large Aperture library. I would request you to create or export Aperture Library into smaller libraries and then import then into Lightroom and see if this helps.
From what I have researched, this is not a large library. I see many users describing their's exceeding 500GB to 1+TB. So that really should not be the issue.
Since my post:
- I have now completely rebuild my Aperture Library. Again, Same Error and failure.
- I tried your suggestion, and exported the library into 3 smaller libraries. I tried importing each one, and in every case had the same failure.
Frustrated. Other suggestions?
Lightroom version: CC 2015.3 [ 1052427 ]
Operating system: Mac OS 10
Version: 10.11 
Application architecture: x64
Logical processor count: 8
Processor speed: 2.8 GHz
Built-in memory: 16,384.0 MB
Real memory available to Lightroom: 16,384.0 MB
Real memory used by Lightroom: 458.5 MB (2.7%)
Virtual memory used by Lightroom: 2,026.5 MB
Memory cache size: 15.9 MB
Maximum thread count used by Camera Raw: 8
Camera Raw SIMD optimization: SSE2,AVX,AVX2
Displays: 1) 2560x1440, 2) 2880x1800
Graphics Processor Info:
AMD Radeon R9 M370X OpenGL Engine
That thread does not actually say anything about a workaround or solution. Really frustrated.
Trying to import an Aperture library tonight with the same error. How did you resolve this issue?
Thanks, appreciate any info!
As you can read further up in the message thread you've added to, if your library is relatively large try breaking it into smaller libraries and see if those smaller ones will import.
My library is not large on the scale of some other users (60gb).
I am happy to report, that after some more digging, I did find some helpful information.
I repaired my Aperture Library & Permissions, and that seemed to do the trick. Importing my library as I type.
It actually never worked for me. I did break mine down into smaller libraries, but it never worked. I had been told that there would be some update to the import function to address this, but if there has, it does not work. As a result, I chose not to use LR. I just decided to try again, almost a year later with all the latest OS Sierra and LR CC, but still same error. Frustrating.