diff --git a/src/main/java/se/oru/coordination/coordination_oru/AbstractTrajectoryEnvelopeCoordinator.java b/src/main/java/se/oru/coordination/coordination_oru/AbstractTrajectoryEnvelopeCoordinator.java
index b5790f02b..6499abccb 100644
--- a/src/main/java/se/oru/coordination/coordination_oru/AbstractTrajectoryEnvelopeCoordinator.java
+++ b/src/main/java/se/oru/coordination/coordination_oru/AbstractTrajectoryEnvelopeCoordinator.java
@@ -116,6 +116,7 @@ public abstract class AbstractTrajectoryEnvelopeCoordinator {
 
 	protected HashSet<Integer> muted = new HashSet<Integer>();
 
+	protected boolean updateAllPostedMissionsOnce = false;
 	protected boolean yieldIfParking = true;
 	protected boolean checkEscapePoses = true;
 
@@ -241,6 +242,11 @@ public int getControlPeriod() {
 	public void setYieldIfParking(boolean value) {
 		this.yieldIfParking = value;
 	}
+	
+	//FIXME
+	public void setUpdateAllPostedMissionsOnce(boolean value) {
+		this.updateAllPostedMissionsOnce = value;
+	}
 
 	/**
 	 * Set whether completely overlapping paths should lead to a warning.
@@ -1734,17 +1740,27 @@ public void run() {
 				while (true) {
 					synchronized (solver) {	
 						if (!missionsPool.isEmpty()) {
-							//get the oldest posted mission
-							int oldestMissionRobotID = -1;
-							long oldestMissionTime = Long.MAX_VALUE;
-							for (int robotID : missionsPool.keySet()) {
-								if (missionsPool.get(robotID).getSecond().compareTo(oldestMissionTime) < 0) {
-									oldestMissionTime = missionsPool.get(robotID).getSecond().longValue();
-									oldestMissionRobotID = robotID;
+							
+							//FIXME critical sections should be computed incrementally/asynchronously
+							if (updateAllPostedMissionsOnce) {
+								for (int robotID : missionsPool.keySet()) {
+									envelopesToTrack.add(missionsPool.get(robotID).getFirst());
+								}
+								missionsPool.clear();
+							}
+							else {
+								//get the oldest posted mission (use TreeSet)
+								int oldestMissionRobotID = -1;
+								long oldestMissionTime = Long.MAX_VALUE;
+								for (int robotID : missionsPool.keySet()) {
+									if (missionsPool.get(robotID).getSecond().compareTo(oldestMissionTime) < 0) {
+										oldestMissionTime = missionsPool.get(robotID).getSecond().longValue();
+										oldestMissionRobotID = robotID;
+									}
 								}
+								envelopesToTrack.add(missionsPool.get(oldestMissionRobotID).getFirst());
+								missionsPool.remove(oldestMissionRobotID);
 							}
-							envelopesToTrack.add(missionsPool.get(oldestMissionRobotID).getFirst());
-							missionsPool.remove(oldestMissionRobotID);
 							computeCriticalSections();
 							startTrackingAddedMissions();
 						}
diff --git a/src/main/java/se/oru/coordination/coordination_oru/motionplanning/AbstractMotionPlanner.java b/src/main/java/se/oru/coordination/coordination_oru/motionplanning/AbstractMotionPlanner.java
index 9dff46088..2b5a504c1 100644
--- a/src/main/java/se/oru/coordination/coordination_oru/motionplanning/AbstractMotionPlanner.java
+++ b/src/main/java/se/oru/coordination/coordination_oru/motionplanning/AbstractMotionPlanner.java
@@ -95,6 +95,7 @@ public PoseSteering[] getPath() {
 	}
 	
 	public PoseSteering[] getPathInv() {
+		if (this.pathPS == null) return this.pathPS;
 		ArrayList<PoseSteering> inv = new ArrayList<PoseSteering>();
 		for (PoseSteering ps : this.pathPS) inv.add(ps);
 		Collections.reverse(inv);
diff --git a/src/main/java/se/oru/coordination/coordination_oru/tests/icaps2018/talk/RandomPathsInMap.java b/src/main/java/se/oru/coordination/coordination_oru/tests/icaps2018/talk/RandomPathsInMap.java
index c7f3fdc5d..a0b1ac17b 100644
--- a/src/main/java/se/oru/coordination/coordination_oru/tests/icaps2018/talk/RandomPathsInMap.java
+++ b/src/main/java/se/oru/coordination/coordination_oru/tests/icaps2018/talk/RandomPathsInMap.java
@@ -226,6 +226,9 @@ public int compare(RobotAtCriticalSection o1, RobotAtCriticalSection o2) {
 				}
 				else rsp.setGoals(endLoc);
 				rsp.plan();
+				if (rsp.getPath() == null) {
+					throw new Error("No path found.");
+				}
 				path = rsp.getPath();
 				pathInv = rsp.getPathInv();
 				if (cachePaths) {