DWR 3.0.2 Upgrade - "Incomplete reply from server"

Hi all,

Our setup: DWR 3.0.2, Java 1.8, Spring 2.5.6, Websphere

We have upgraded from DWR 2.0.3 to DWR 3.0.2.
It works fine running locally, but not in a test environment. Both have the setup mentioned above.

In the test environment we get the same error in both the application and in the debugging tool (/dwr/index.html).

In the console we get an LogEvent with the following message:
“Incomplete reply from server”

In the network tab we see a request to “hostname:9080/dwr/call/plaincall/__System.generateId.dwr”.
With the following Request Payload:
image

With the following Response:
//#DWR-REPLY
//#DWR-START#
(function(){
if(!window.dwr)return;
var dwr=window.dwr._[0];
dwr.engine.remote.handleCallback({bytes:’/dwr/download/FZX4!kmKXGmvVn59VsApgwxXr2BALtLc!In-2’,empty:{}},{bytes:’/dwr/download/fY5UoiwB5T0C~Inb4RM4whyIkOAVLtLc!In-3’,empty:{}},{bytes:’/dwr/download/6exJBVjct0OBQsDZ8bNmsBp9vy4UMtLc!In’,empty:{}});
})();
//#DWR-END#

Which is also significantly different than the response locally:
//#DWR-REPLY
//#DWR-START#
(function(){
if(!window.dwr)return;
var dwr=window.dwr._[0];
dwr.engine.remote.handleCallback(“0”,“0”,“9dVqWXBwXaZZS~gyK!2cuRsQncu8yMwp!In”);
})();
//#DWR-END#

No other requests are made in the test environment. Caused by the weird arguments to the handleCallback function in the first response, it seems.
We don’t see anything in the logs - even using the DWR accessLogLevel.

Hope you can help us out.