406: Not Acceptable error for `/subscriptions/{subscriptionId}/resourcegroups/{resourceGroupName}/providers/{resourceProviderNamespace}/{parentResourceType}/{parentResource}/providers/Microsoft.SerialConsole/serialPorts/{serialPort}/connect`

@spledfx receives 406 when using Python SDK that is related with [/subscriptions/{subscriptionId}/resourcegroups/{resourceGroupName}/providers/{resourceProviderNamespace}/{parentResourceType}/{parentResource}/providers/Microsoft.SerialConsole/serialPorts/{serialPort}/connect](https://github.com/Azure/azure-rest-api-specs/blob/23d88533ddfde4d1565a897fe95d42fb0d9333e5/specification/serialconsole/resource-manager/Microsoft.SerialConsole/stable/2018-05-01/serialport.json#L288). The error message doesn't give detailed message about what goes wrong, so we have to seek help from service team.
Here is full log: https://github.com/Azure/azure-sdk-for-python/issues/31066#issuecomment-1645258157

Start with specification/serialconsole/resource-manager/Microsoft.SerialConsole/stable/2018-05-01/serialport.json at the connect operation around line 288, then review the linked Azure SDK for Python log. Determine what information is missing from the 406 response and what specification or service clarification would be required; the issue is complete when the cause and needed change are documented.

Written by the indexing model from the issue text.