On both switches, it is required to have a single route to the TFTP server (By default this is 10.92.100.60, but individual configurations may differ).
This is needed because there are issues with Aruba ECMP hashing and TFTP traffic.
(switch#)
show ip route 10.92.100.60
Example output:
Displaying ipv4 routes selected for forwarding
'[x/y]' denotes [distance/metric]
10.92.100.60/32, vrf default, tag 0
via 10.252.1.9, [70/0], bgp
10.252.1.9 is pingable.