aperture stuck importing photos, loading asset frozen

Look at Aperture 3: Troubleshooting Basics try the permission repair, the library repair and move the plist file out of your Preferences folder (the link explains how to do this). See if that helps.

If not create a new empty Aperture library and open Aperture on it, does the problem still happen?

if so crete a new user on your system log in as that user and run Aperture, does the same problem happen?

For iPhoto libraries it used to help, to remove the current "Importing" folder from the library package. Try, if this will help for your Aperture library.

See this post by LarryHN how to do it:

TS3745 Re: iphoto library error message???

I found a sequence that has worked for me a couple of times, first with a managed library and also with a referenced library. Once you see in the Activity window that nothing is progressing, select the root Folder Import and hit Pause Task. This should pause everything. Now, go and try to Quit Aperture. This will send you a warning that you are Importing, etc. and give you either Quit or Continue. Select Continue.

Go back to the Activity window and select the root Folder Import and hit Run Task. It should be working again.

Thank you for your reply.

I'm not sure exactly what folder he is refering to. The closest I could find was named "Auto Import". Removed this folder. Close but no cigar, still gets stuck on generating preview...

But I will continue to investigate.

How long have you waited? How many images are you trying to import?

Camera or card reader? Have tou rebooted your machine since this started happening? Tried a different usb port and cable?

I'd give all these a shot to try and eliminate the obvious.

It's great that this works for you, but I had no luck with this trick. Thanks anyway.

Apple, are you hearing our cries for help? 🙂

That folder is not always there - only when there is really an interrupted import going on. So it will not always work.