Cisco 4321 router Upgradation problem from 16.6.4 to 17.3.4a

[NitinPowar99674]

Dear Experts,

We have upgraded the cisco 4321 router from 16.6.4 to 17.3.4a.

The router successfully upgraded to 17.3.4a but it erase all configurations. Also asking for username and password which not accessed through older credentials. 

Also, it's showing error like '%BOOT-0-BOOT_NOSPACE'

After we decide to perform password recovery activity but it 'configure terminal' cmd not working

So please assist.

[Leo Laohoo]

Raise a TAC Case.  I've never heard of such behaviour before.

[balaji.bandi]

i see some bug reported:  https://bst.cloudapps.cisco.com/bugsearch/bug/CSCvs81967

as suggested worth opening a TAC case to assist better.