Rudder

Webapp log show following error:

java.lang.NumberFormatException: For input string: "Error when trying to contact internal remote-run API: null" 
        at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
        at java.lang.Integer.parseInt(Integer.java:580)
        at java.lang.Byte.parseByte(Byte.java:149)
        at java.lang.Byte.parseByte(Byte.java:175)
        at scala.collection.immutable.StringLike.toByte(StringLike.scala:297)
        at scala.collection.immutable.StringLike.toByte$(StringLike.scala:297)
        at scala.collection.immutable.StringOps.toByte(StringOps.scala:29)
        at com.normation.rudder.web.rest.node.NodeApiService8.runResponse(NodeAPIService8.scala:119)
        at com.normation.rudder.web.rest.node.NodeApiService8.$anonfun$runNode$4(NodeAPIService8.scala:155)
        at com.normation.rudder.web.rest.node.NodeApiService8.$anonfun$runNode$4$adapted(NodeAPIService8.scala:155)
        at net.liftweb.http.LiftServlet.sendResponse(LiftServlet.scala:1040)
        at net.liftweb.http.LiftServlet.doService(LiftServlet.scala:451)
        at net.liftweb.http.LiftServlet.$anonfun$service$2(LiftServlet.scala:157)
        at net.liftweb.util.TimeHelpers.calcTime(TimeHelpers.scala:427)
...
        at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:154)
        at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:116)
        at org.eclipse.jetty.server.Server.handle(Server.java:369)
        at org.eclipse.jetty.server.AbstractHttpConnection.handleRequest(AbstractHttpConnection.java:464)
        at org.eclipse.jetty.server.AbstractHttpConnection.headerComplete(AbstractHttpConnection.java:913)
        at org.eclipse.jetty.server.AbstractHttpConnection$RequestHandler.headerComplete(AbstractHttpConnection.java:975)
        at org.eclipse.jetty.http.HttpParser.parseNext(HttpParser.java:641)
        at org.eclipse.jetty.http.HttpParser.parseAvailable(HttpParser.java:231)
        at org.eclipse.jetty.server.AsyncHttpConnection.handle(AsyncHttpConnection.java:82)
        at org.eclipse.jetty.io.nio.SelectChannelEndPoint.handle(SelectChannelEndPoint.java:667)
        at org.eclipse.jetty.io.nio.SelectChannelEndPoint$1.run(SelectChannelEndPoint.java:52)
        at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:608)
        at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:543)
        at java.lang.Thread.run(Thread.java:745)