Cisco ASA 5505 backup failed with error "Failed to enter enable mode"

We are using Kiwi Cattools v.3.11.2 for backup of our Network devices.

We recently noticed one of the Cisco ASA(ASA 5515-X)'s backup failed with error "Failed to enter enable mode". This is only happens occasionally and all other times it's fine.

Any suggestions/fix  much appreciated.