Start session error kurento

On occasions when I start a class the system returns the following error:
ERROR: [KurentoClient] Exception connecting to WebSocket server ws: // localhost: 8888 / kurento. Code: 204 in Request: method: joinRoom params: {My data}
request: undefined

and I have to restart openvidu and kurento, do you know why?
openvidu 2.11.0

En ocaciones cuando inicio una clase el sistema me retorna el siguiente error:
ERROR:[KurentoClient] Exception connecting to WebSocket server ws://localhost:8888/kurento. Code: 204 in Request: method:joinRoom params: {My data}
request:undefined

y tengo que reiniciar openvidu y kurento, saben a que se debe?

Please use 2.12 version as we have improved KMS stabillity and reduced crashes.