...
To fix this, you must change the Thrift client and server ports of Gateway and Key Manager to the same value. In this case, the difference between the two offsets is 3, so you can either increase the default Thrift client port by 3 or else reduce the Thrift server port by 3.
Changing the offset of the Workflow Callback Service
The API Manager has a Service which listens for workflow callbacks. This service configuration can be found at <AM_HOME>/repository/deployment/server/synapse-configs/default/proxy-services/WorkflowCallbackService.xml. Open this file and change the port value of the <address uri accordingly.
Ex: <address uri="https://localhost:9445/store/site/blocks/workflow/workflow-listener/ajax/workflow-listener.jag" format="rest"/>
For a list of all default ports opened in WSO2 API Manager, see Default Ports of WSO2 Products.