Possible root cause:

The most common occurrence of this error is associated to the usage (or not) of IPv6 and an incorrect definition of the “localhost” address.

Possible solutions:

If IPv6 is not used, remove the environment variable “SAP_IPv6_Active” at the end user’s computer. All SAP GUI and SAP Logon windows must be closed, and the SAP Logon must be started again after the environment variable was removed.
If IPv6 is used, edit the “hosts” file (C:\Windows\System32\drivers\etc\hosts) and confirm that the correct definitions of “localhost” are maintained, ensuring that the IPv6 definition comes before the IPv4 definition:
```
::1			localhost
127.0.0.1	localhost
```

As the issue is being related to the functions on the network layer of SAP, BC-CST-NI or BC-NET could also be involved, especially when “DirectAccess” is being configured (SAP KBA 2325532- Microsoft DirectAccess and SAP Load Balancing).