spawnModel Error in Robotics System Toolbox

I follow the instruction in add-build-and-remove-objects-in-gazebo, and the following commands work successfully.

rosinit(ipaddress)
gazebo = ExampleHelperGazeboCommunicator;
ball = ExampleHelperGazeboModel('Ball')
spherelink = addLink(ball,'sphere',1,'color',[0 0 1 1])

But when I run the next command "spawnModel(gazebo,ball,[8.5,0,1])", the errors show up:

Error using ExampleHelperGazeboCommunicator/startModelServices (line 334)
Failed to create a /gazebo/get_model_state service client.

Error in ExampleHelperGazeboCommunicator/spawnModel (line 290)
                startModelServices(obj);

[ERROR] ServiceClientHandshakeHandler - Service client handshake failed: client wants service /gazebo/get_model_state to have md5sum af0f702011820738976b120226dc9d96, but it has 4c515e936d3319c9610c559c60bfc3d4. Dropping connection.

I use matlab 2018b, Robotics System Toolbox2.1 on win10, and ROS melodic, gazebo9 in virtualbox, which are all newest version, but still encounter that problem. Does anyone know how to solve it?

Answer 1

[Chin-Wei Chang]

Solution is here Update MATLAB's ROS Messages

Replace rosjava_messages.jar and then spawn model successfully.

[José Hugo Soares de Jesus]

Do you know what´s the correct path in MacOS to put the java file?