I am having the same issue creating a 10.7.4 Netboot image. Same symptoms. My server is a 10.7.4 Server running 8.52 of the JSS. I have recreated the 10.7.4 client I am using as my netboot source 4 different times from scratch. I have tried the manual creation and the Automator Action creation. Same results.

Ok, so started all over this morning:
• Made a brand new image using Composer 6.01 (oh yes baby, I keep that puppy in my back pocket!!).. took a real L O N G time to do it.
• Followed the steps in the Casper NetBoot Automater Action v1.1
and get the same results
:(

HOWEVER ....

• Boot up the laptop that the netboot was made (MacBook Pro9,2) and run Casper Imaging while I attached a Target Mode MacBook Pro9,2 (we bought two)... it works just fine.

Now here is the funny part:
• If I netboot a MacMini3,1 with the 10.7.4 NetBoot images I have been struggling with... it works as it should.

Seems like it doesn't like the new hardware which it was made from?

Think I'm gonna call JAMF on Monday.
Whacha think?

Hey Pat, are you checking "Erase Macintosh HD" by chance? I've noticed that my 10.7.4 NBI will fail with the same error if I have that checked. I quit out of Casper Imaging, go into Disk Utility on the NBI and try to erase the drive, and of course receive the "This drive cannot be unmounted", or whatever it says.

I boot then from a different NBI (a 10.6.8 one I have) and I can erase the drive in Disk Utility. Boot back into the 10.7.4 NBI and voilá, CI works fine.

I'm certain I have "Diskless" checked on the server hosting the 10.7.4 NBI, but I will double check later to make sure.

Just wondering if this is what you are running into.

I had EXACTLY the same problem with my 10.7.4 server using Casper 8.52. I never could figure it out, even with the help of JAMF. I ended up using my old JSS (10.6.8) as my NetBoot server, which works perfectly, even with the very same .nbi image.

I had this same issue starting a couple of weeks ago. OS X10.6.8 net boot with Casper Imaging worked fine. Os X 10.7.4 gave me the "An exception of class NilObject Exception was not handled. The application must shut down." error. After rebuilding my netboot image a couple of times I went back to check the settings on my OS X server that runs netboot (OS X 10.6.8 Server on a MacPro). I played around with the share point settings (Protocol Options) for my CasperShare and NetBootSP0 shares and that fixed the problem. Unfortunately I didn't write down which changes I had made (bad sysadmin!) as I was pretty frustrated with the situation and just glad it was working again.
So not sure if that helps, but go take a look at your share point protocol option settings and see if anything looks amiss.

This is tickling a memory in the back of my head. I think checking "Diskless" on the netboot image in Server Admin did the trick.

And I just double checked my NBI settings in SA, and Diskless is checked already. And the server is a 10.6.8 server.

I'll try moving the NBI over to the NetSUS appliance and my 10.7 server and see if either of those corrects the problem.

I spent most of today dealing with this. The problem occurs when you do a diskless netboot, but it fails over to the local drive. Since it creates a shadow file on the local disk, you can't unmount it to erase or image. To test it, you can boot the system to a firewire drive, partition the internal disk into 2 volumes, boot to your casper netboot set and open disk utility. You will not be able to eject your root volume, but can the second volume. My shares were fine. I could net boot with a 10.6.8 image no problem, etc. The solution I finally found is here:

http://www.macos.utah.edu/documentation/administration/setup_netboot_service_on_mac_os_x_10.6.x_client.x_client/setup_netboot_service_on_mac_os_x_10.6.x_client-diskless_netboot.html

I opened my 10.7.4 netboot set, and sure enough, the rc.netboot file had the issue reported at the utah site. I made the relevant changes, included their script to use a ram disk instead of a network cache and tried again, Wow, a total revelation. Not only does it work with no problem, but since the shadow file is a ramdisk, it is super fast. Hope this helps-

My server is 10.6.8
My netboot set is 10.7.4 built from a fresh mac app store copy today.
iMac (mid 2010), no system OS

Thanks a TON. Replacing the rc.netboot did the trick!

Hi all,

OK.. based on everything I've read here and done I finally got it.
Thanks to dremington for the link above which seems to have solved it and my jss is back to normal (for me that is)

Thanks again!!!

-pat

Hi All,

dremington Link fixed the problem,

Thanks heaps dremington

Isaac