In jboss/.../deploy/server.log, there is not any exception about the error.
I don't know why Guvnor can't find the designer.
This error appears all the time.
The address of my accessing Guvnor: http://localhost:8080/drools-guvnor/org.drools.guvnor.Guvnor/Guvnor.html#asset=e3cd9a8f-9b01-4ffe-abde-d5c5adc5638b