I think there is some error on the next document:
https://www.cisco.com/c/en/us/td/docs/dcn/nx-os/nexus9000/103x/upgrade/cisco-nexus-9000-nx-os-software-upgrade-downgrade-guide-103x/m_converting_from_cisco_nx-os_to_aci_mode_10x.html
I tried the procedure in two different switches and have the same problem.
First always go to bash4.2
System is coming up ... Please wait ...
....System is coming up ... Please wait ...
....System is coming up ... Please wait ...
....System is coming up ... Please wait ...
....System is coming up ... Please wait ...
....System is coming up ... Please wait ...
....System is coming up ... Please wait ...
....System is coming up ... Please wait ...
....System is coming up ... Please wait ...
....System is coming up ... Please wait ...
....System is coming up ... Please wait ...
....System is coming up ... Please wait ...
..bash-4.2#
Then i try to boot from tftp:
loader > boot tftp://192.168.113.1:/nxos64-cs.10.4.3.F.bin
Security Lock
Booting tftp://192.168.113.1:/nxos64-cs.10.4.3.F.bin
Trying netboot
Filename: /nxos64-cs.10.4.3.F.bin
Address: 192.168.113.51
Netmask: 255.255.255.0
Server: 192.168.113.1
Gateway: 192.168.113.1
Filesystem type is tftp, using whole disk
Formed cmdline console=ttyS0,9600n8nn loader_ver="5.47" quiet recovery=1 card_index=21134 ksimg=tftp://192.168.113.1:/nxos64-cs.10.4.3.F.bin
tftp fragment = 0
blksize = 1024
filemax = ffffffff
................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................Image valid
Image Signature verification was Successful.
Well seems to go very well but... the system reboots and...
Saving image for img-sync ...
cat: /var/sysmgr/ftp/img-sync/img_len_sync.txt: No such file or directory
cat: /var/sysmgr/ftp/img-sync/img_len_sync.txt: No such file or directory
cat: /var/sysmgr/ftp/img-sync/img_len_sync.txt: No such file or directory
TFTP download failed with Max retries. Please diagnose your network problem first.
Rebooting system...
Always same behavior... i will try with a pendrive.
