Gateway status is "Starting" after upgrading from 8.1 to 8.4

Issue/Introduction:

Gateway status is "Starting" after upgrading from 8.1 to 8.4 and restoring copy of database. Was able to login to 8.4 policy manager after upgrade, but status changed to Starting after restoring copy of database from another gateway. Gateway version the database copy came from was 8.1 and was restored to gateway running 8.4.

Used SSG menu to upgrade DB it reported as successful however the DB is not reflecting the upgrade

                mysql> SELECT * FROM ssg_version;
                +-----------------+
                | current_version |
                +-----------------+
                | 8.1.02          |
                +-----------------+
                1 row in set (0.04 sec)

Environment:

APIM Gateway 8.1
APIM Gateway 8.4

Resolution:

Before updating the database needed to so the following in mysql

>mysql ssg
mysql>drop table DATABASECHANGELOG;
mysql>drop table policy_backed_service_operation;
mysql>drop table policy_backed_service;
mysql>drop table cassandra_connection;
mysql>drop table server_module_file_state;
mysql>drop table server_module_file;
mysql>drop table server_module_file_data;

Then upgrade the DB from the ssg menu and it was success. And updated the ssg_version table.

Additional Information:

After update validate DB version
mysql> SELECT * FROM ssg_version;
+-----------------+
| current_version |
+-----------------+
| 8.4.00 |
+-----------------+
1 row in set (0.00 sec)