When Using Server Side Extensions / Analytic Connections, the Error "Failed to initialize gRPC communication for SSEPlugin" is being printed to the logs

When Using Server Side Extensions / Analytic Connections, the Error "Failed to initialize gRPC communication for SSEPlugin" is being printed to the logs, what does this mean and what could the root cause be?

Environments:

• Qlik Sense Enterprise, June2017 and higher

This error means that Qlik Sense was not able to establish a connection to your Server Side Extension (or wherever it is hosted). The root cause most-likely lies in your network, here are some possible troubleshooting steps:

• Check the port communication Qlik Sense -> SSE server and SSE server -> Qlik Sense (see How To Check Open Ports Using PowerShell).
• Verify if a 3rd-party network appliance (such as a load balancer) is part of the network communication between Sense and the SSE plugin; try testing locally on the Qlik Sense Server to remove this factor.
• If in a multi-node installation, verify if this happens from all nodes or only the central node, verify communication between the rim and central nodes.
• If the above works fine, try testing with one of the example SSE plugins to see if the issue persists with the example or if it only occurs with your SSE plugin (to verify if your plugin may be the issue). Precompiled versions of the plugin are available in the Releases section of the repository, but please note that these are not officially supported.

Note: Qlik does NOT support the configuration or implementation of non-Qlik or Operating System related software. 

Note: Debugging or writing custom code is supported by the Qlik Professional Services or Presales teams. No Support or maintenance is implied or provided. Further customization is expected to be necessary and it is the responsibility of the end administrator to test and implement their custom code for their specific use case.