Error:

0042-001 nim: processing error encountered on "master":
   0042-001 m_alloc_boot: processing error encountered on "master":
   0042-157 c_alloc_boot: unable to access the "/tftpboot/spot.chrp.64.ent" file

Description:

NIM Client`s netboot_kernel has configured as 64, however spot created from the mksysb of the NIM client which has configured  netboot_kernel as "mp". So created spot do not have "/tftpboot/spot.chrp.64.ent" file.

Solution:

Change the "netboot_kernel" characteristic of the NIM Client from "64" to "mp" on which you are trying to install from this SPOT.

nim -o change -a netboot_kernel=mp NIM_client