RPC error started happening

I have been using Traccar for about a year now without issue until 2am this morning. The wrapper log below shows the error I'm getting. Nothing appears to have changed since yesterday. I can log in and get positional data up to the point it stopped working. Any ideas?

Extract from wrapper log:

INFO   | jvm 1    | 2015/08/12 14:35:26 | WrapperManager: Initializing...
INFO   | jvm 1    | 2015/08/12 14:35:27 | 2015-08-12 14:35:27.049:INFO:oejs.Server:jetty-8.1.16.v20140903
INFO   | jvm 1    | 2015/08/12 14:35:27 | 2015-08-12 14:35:27.083:INFO:oejw.WebInfConfiguration:Extract jar:file:/opt/traccar/traccar-web.war!/ to /tmp/jetty-0.0.0.0-8082-traccar-web.war-_-any-/webapp
INFO   | jvm 1    | 2015/08/12 14:35:28 | 2015-08-12 14:35:28.683:INFO:oejw.StandardDescriptorProcessor:NO JSP Support for /, did not find org.apache.jasper.servlet.JspServlet
INFO   | jvm 1    | 2015/08/12 14:35:28 | 2015-08-12 14:35:28.739:INFO:oejs.AbstractConnector:Started SelectChannelConnector@0.0.0.0:8082
INFO   | jvm 1    | 2015/08/12 14:35:38 | 2015-08-12 14:35:38.897:WARN:/:Exception while dispatching incoming RPC call
INFO   | jvm 1    | 2015/08/12 14:35:38 | com.google.gwt.user.server.rpc.UnexpectedException: Service method 'public abstract java.util.List org.traccar.web.client.model.DataService.getLatestPositions()' threw an unexpected exception: java.lang.IllegalStateException

Thanks

What version of Traccar are you using? Are you using default web interface?

Hi
Sorry for the late response, I'm still using version 2.1 as I need some time to amalgamate all the data into 1 place in the new format. I am using the standard web interface running on a centOS VPS.
The system started working again about an hour after I posted and has been ok ever since. It seems the local gprs network was off for some reason.
Thanks