The error is caused by the missing server attribute "username".
To fix the issue navigate to
Healthwatch >
Grafana Configuration >
Server attributes.
You will see something similar to:
member_of = "memberOf"
email = "email"
Add "username" to the the box mapped to any unique attribute that exists for the user in LDAP.
For example:
member_of = "memberOf"
email = "email"
username = "mail"
Save the changes and
Apply Changes for the Healthwatch 2 tile.
For more information, refer to
LDAP Authentication - Troubleshooting.