Upgrading from confd-4.0.7.1 to confd-6.4.2

hi,
I am planning to upgrade the confd, there are some changes in Yang which got depreceated like tailf:id-value, but will there be any issues with the new retaining the running configurations ?

Can you suggest some pointers where i can look to ensure whether i have taken care of all those ?

Regards
Shaffath S

With the upgrade from such an old release, it is recommended to file a ticket with our support team.