One of the reasons for this issue is due to unconfigured krb5.conf file and missing keytab file in the upgraded Spotfire Server location. Make sure to copy the krb5.conf and keytab files from the existing "[Spotfire Server installation folder\jdk\jre\lib\security" folder to the "\jdk\jre\lib\security" folder location of the upgraded Spotfire server folders.
Note: This is based on the assumption that the new version of the Spotfire Server is installed on the same machine as the old one.
Note: If this doesn't resolve the issue, enable debug logging on the Spotfire Server and check the server logs for additional clues. Review the
Spotfire Server Installation and Configuration manual for additional information on logging and monitoring.