diff --git a/ch.psi.fda/src/main/java/ch/psi/fda/rest/ExecutionEngine.java b/ch.psi.fda/src/main/java/ch/psi/fda/rest/ExecutionEngine.java
index 09c913a..ee56621 100644
--- a/ch.psi.fda/src/main/java/ch/psi/fda/rest/ExecutionEngine.java
+++ b/ch.psi.fda/src/main/java/ch/psi/fda/rest/ExecutionEngine.java
@@ -33,6 +33,7 @@ import java.util.logging.Level;
 import java.util.logging.Logger;
 
 import javax.inject.Inject;
+import javax.ws.rs.WebApplicationException;
 
 import ch.psi.fda.edescriptor.EDescriptor;
 import ch.psi.jcae.ChannelService;
@@ -100,19 +101,23 @@ public class ExecutionEngine {
 		logger.info("Terminate TrackingId: "+trackingId);
 		
 		if(!erequests.containsKey(trackingId)){
-			throw new IllegalArgumentException("There is no request for tracking id "+trackingId);
+			throw new WebApplicationException("There is no request for tracking id "+trackingId, 404);
 		}
 		
 		final JobEntry f = erequests.get(trackingId);
 		f.getFuture().cancel(true);
 		f.getJob().stop();
 		
+		
 		try{
 			f.getFuture().get(10, TimeUnit.SECONDS);
 		}
 		catch(CancellationException | InterruptedException | ExecutionException | TimeoutException e){
 			// Nothing to be done here
+			throw new WebApplicationException("Unable to terminate job");
 		}
+		
+		erequests.remove(trackingId);
 	}
 
 	public boolean isActive(String trackingId) {