Cannot login to the switch with root account via CLI running on FOS 8.x

1. Login via admin.
2. Check the root access:
#rootaccess --show
RootAccess : none
(when the root access isn't allowed it would return output "none")
3. To allow the root access:
There will be 3 options:

• none 
• consoleonly 
• all

These above options denies/permits access to root account over console and management interface.

select option "all"
#rootaccess --set all
Changing root access permission will terminate existing sessions.
Please confirm to proceed (yes, y, no, n):[no]
Enter "yes" to confirm to allow the root access. 

3. Recheck confirm the root access:
#rootaccess --show
RootAccess: all

When the outout "all" is returned, the root access is allowed.
 

When trying to access the switch on CLI via ROOT account, the putty session disappears with message :
"Access for this account on this interface is disabled; please contact your system administrator"

The putty session automatically disappears as soon as the password is entered, leaving no time for the user to read the message.

The root access isn't allowed on the switch as it is set to "none" to allow the root access, the user needs to login via admin and allow root access on the switch:

Once the root access is allowed, the user can log into the root account.