415 Unsupported Media Type

[Xeviva]

I have just tried to start this tool again, having not run any tests for about 6 months and my existing tests no longer run.
I am getting errors of 415 Unsupported Media Type from the bot's response.

The Json response from my bot is:

{ "type": "message", "timestamp": "2019-09-02T16:16:53.981189+00:00", "serviceUrl": "https://93b251d9.ngrok.io", "channelId": "emulator", "from": { "id": "default-bot" }, "conversation": { "id": "a719fc13-030b-483c-b347-9f7cddd88e99" }, "recipient": { "id": "user-nGmWB" }, "text": "Hello Stranger", "attachments": [], "entities": [] }

and the response is:
`HTTP/1.1 415 Unsupported Media Type
Date: Mon, 02 Sep 2019 16:16:00 GMT
Cache-Control: must-revalidate,no-cache,no-store
Content-Type: text/html;charset=iso-8859-1
Content-Length: 405
Server: Jetty(9.4.z-SNAPSHOT)

<title>Error 415 Unsupported Media Type</title>

HTTP ERROR 415

Problem accessing /v3/conversations/a719fc13-030b-483c-b347-9f7cddd88e99/activities. Reason:

    Unsupported Media Type

---

Powered by Jetty:// 9.4.z-SNAPSHOT

---

`

I have updated JMeter, JRE and this plugin to the latest version.
Any ideas what could be wrong here?

[CraigGraw]

I have also seen this issue when sending a message to a conversation. It works for replies to an activity but not for sending a new activity.