I am trying to upgrade a SLES 11 SP4 system to SLES 12 SP2 under z/VM 6.4 and am getting the following in the "System Probing" screen.

Unable to create repository
from URL 'nfs://'.

[SLES12-SP2-12.2-0|nfs://] Valid metadata not found at specified URL
 - Can't hardlink/copy /var/adm/mount/AP_0x3xbBTK/suse/setup/descr/appdata-icons.tar.gz to /var/cache/zypp/raw/SLES12-SP2-12.2-0OcK9aD
 - Can't provide /suse/setup/descr/appdata-icons.tar.gz

Try again?
My SMT server is hosting the .iso file for SLES 12, which I have mounted and made available via NFS. I have verified that the installation media is available via NFS from a different zLinux server.

Here is the relevant entry from /etc/exports:
Here is the relevant entry from /etc/fstab:
/srv/www/htdocs/iso_repository/sles12/SLE-12-SP2-Server-DVD-s390x-GM-DVD1.iso  /media/s390x/sles12sp2/dvd1 udf,iso9660  ro,loop  0  0
What is confusing is that I used the same installation method when I originally installed SLES 11 (base).

I am using the SLES12 EXEC with a PARMFILE to boot the SLES 12 SP2 installation system. Here is the contents of my PARMFILE:
ramdisk_size=131072 root=/dev/ram1 ro init=/linuxrc term=dumb   
vmpoff=logoff hostname=wcs-mf-syssoft1 hostip=       
gateway= nameserver=                     
instnetdev=osa osainterface=qdio layer2=1 portno=0 
netmask= broadcast=                   
readchannel=0.0.1f00 writechannel=0.0.1f01 datachannel=0.0.1f02 
usessh=1 sshpassword=temppswd linuxrclog=/dev/console           
I searched the forums and see that there have been a few issues, from February 2017, raised on this same issue but there have been no responses. I'm hoping that someone can point out what I need to change to get past this problem.