Response code NL-NETWORK-01, when using the POST method in the API tests

I am sending the followint POST command:

POST https://petstore.swagger.io/v2/user
User-Agent: Jetty/9.3.7.v20160115NeotysEdition.61
:
:
Content-Type: application/json
Content-Length: 174

{"id": 1257, "username": "Uname4", "firstName": "FName5", "lastName": "LName6", "email": "Emai8l@email.com",
"password": "user12347", "phone": "9944556633", "userStatus": 0}

This response I will get:

Error detected by NeoLoad
Error Code: NL-NETWORK-01 Message: Network error: An IO error occurred sending the request.
Details: java.io.IOException: protocol_error

Error while initializing client certificates java.io.IOException: toDerInputStream rejects tag type 45

I have done the following:

In the NL preferences I am using certificate NeoLoad_Root_CA.cer for both recording and runtime.

Is something still missing?