Some of the common SPNego related questions surrounding errors and warnings.
Unknown.
For Firefox, type about:config
make the "network.negotiate-auth.delegation-uris" value empty.
The krb5.conf file is not found or configured.
Look for your settings such as the system property "java.security.krb5.conf" is pointing to the right krb5.conf file (Server Side)
Export environment variable KRB5_CONFIG should point to the krb5.conf file for Client side login.