diff --git a/core/net/src/main/java/org/onosproject/net/flowobjective/impl/FlowObjectiveManager.java b/core/net/src/main/java/org/onosproject/net/flowobjective/impl/FlowObjectiveManager.java
index d8a0dec..97c40d2 100644
--- a/core/net/src/main/java/org/onosproject/net/flowobjective/impl/FlowObjectiveManager.java
+++ b/core/net/src/main/java/org/onosproject/net/flowobjective/impl/FlowObjectiveManager.java
@@ -16,6 +16,7 @@
 package org.onosproject.net.flowobjective.impl;
 
 import com.google.common.collect.Maps;
+import com.google.common.collect.Sets;
 import org.apache.felix.scr.annotations.Activate;
 import org.apache.felix.scr.annotations.Component;
 import org.apache.felix.scr.annotations.Deactivate;
@@ -55,21 +56,17 @@
 import org.slf4j.LoggerFactory;
 
 import java.util.ArrayList;
-import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Set;
-import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ExecutorService;
 
 import static com.google.common.base.Preconditions.checkNotNull;
 import static java.util.concurrent.Executors.newFixedThreadPool;
 import static org.onlab.util.Tools.groupedThreads;
 import static org.onosproject.security.AppGuard.checkPermission;
-import static org.onosproject.security.AppPermission.Type.*;
-
-
+import static org.onosproject.security.AppPermission.Type.FLOWRULE_WRITE;
 
 /**
  * Provides implementation of the flow objective programming service.
@@ -124,7 +121,7 @@
 
     protected ServiceDirectory serviceDirectory = new DefaultServiceDirectory();
 
-    private Map<Integer, Set<PendingNext>> pendingForwards = Maps.newConcurrentMap();
+    private final Map<Integer, Set<PendingNext>> pendingForwards = Maps.newConcurrentMap();
 
     // local store to track which nextObjectives were sent to which device
     // for debugging purposes
@@ -237,21 +234,33 @@
     public void initPolicy(String policy) {}
 
     private boolean queueObjective(DeviceId deviceId, ForwardingObjective fwd) {
-        if (fwd.nextId() != null &&
-                flowObjectiveStore.getNextGroup(fwd.nextId()) == null) {
-            log.debug("Queuing forwarding objective {} for nextId {} meant for device {}",
-                      fwd.id(), fwd.nextId(), deviceId);
-            // TODO: change to computeIfAbsent
-            Set<PendingNext> newset = Collections.newSetFromMap(
-                                          new ConcurrentHashMap<PendingNext, Boolean>());
-            newset.add(new PendingNext(deviceId, fwd));
-            Set<PendingNext> pnext = pendingForwards.putIfAbsent(fwd.nextId(), newset);
-            if (pnext != null) {
-                pnext.add(new PendingNext(deviceId, fwd));
-            }
-            return true;
+        if (fwd.nextId() == null ||
+                flowObjectiveStore.getNextGroup(fwd.nextId()) != null) {
+            // fast path
+            return false;
         }
-        return false;
+        boolean queued = false;
+        synchronized (pendingForwards) {
+            // double check the flow objective store, because this block could run
+            // after a notification arrives
+            if (flowObjectiveStore.getNextGroup(fwd.nextId()) == null) {
+                pendingForwards.compute(fwd.nextId(), (id, pending) -> {
+                    PendingNext next = new PendingNext(deviceId, fwd);
+                    if (pending == null) {
+                        return Sets.newHashSet(next);
+                    } else {
+                        pending.add(next);
+                        return pending;
+                    }
+                });
+                queued = true;
+            }
+        }
+        if (queued) {
+            log.debug("Queued forwarding objective {} for nextId {} meant for device {}",
+                      fwd.id(), fwd.nextId(), deviceId);
+        }
+        return queued;
     }
 
     // Retrieves the device pipeline behaviour from the cache.
@@ -396,7 +405,11 @@
         public void notify(ObjectiveEvent event) {
             if (event.type() == Type.ADD) {
                 log.debug("Received notification of obj event {}", event);
-                Set<PendingNext> pending = pendingForwards.remove(event.subject());
+                Set<PendingNext> pending;
+                synchronized (pendingForwards) {
+                    // needs to be synchronized for queueObjective lookup
+                    pending = pendingForwards.remove(event.subject());
+                }
 
                 if (pending == null) {
                     log.debug("Nothing pending for this obj event {}", event);
diff --git a/core/net/src/main/java/org/onosproject/net/intent/impl/IntentInstaller.java b/core/net/src/main/java/org/onosproject/net/intent/impl/IntentInstaller.java
index fc5cbd9..68fc06e 100644
--- a/core/net/src/main/java/org/onosproject/net/intent/impl/IntentInstaller.java
+++ b/core/net/src/main/java/org/onosproject/net/intent/impl/IntentInstaller.java
@@ -120,7 +120,7 @@
             // if toInstall was cause of error, then recompile (manage/increment counter, when exceeded -> CORRUPT)
             if (toInstall.isPresent()) {
                 IntentData installData = toInstall.get();
-                log.warn("Failed installation: {} {} on {}",
+                log.warn("Failed installation: {} {} due to {}",
                          installData.key(), installData.intent(), ctx.error());
                 installData.setState(CORRUPT);
                 installData.incrementErrorCount();
@@ -129,7 +129,7 @@
             // if toUninstall was cause of error, then CORRUPT (another job will clean this up)
             if (toUninstall.isPresent()) {
                 IntentData uninstallData = toUninstall.get();
-                log.warn("Failed withdrawal: {} {} on {}",
+                log.warn("Failed withdrawal: {} {} due to {}",
                          uninstallData.key(), uninstallData.intent(), ctx.error());
                 uninstallData.setState(CORRUPT);
                 uninstallData.incrementErrorCount();
@@ -355,6 +355,7 @@
         private class FlowObjectiveInstallationContext implements ObjectiveContext {
             Objective objective;
             DeviceId deviceId;
+            ObjectiveError error;
 
             void setObjective(Objective objective, DeviceId deviceId) {
                 this.objective = objective;
@@ -368,6 +369,7 @@
 
             @Override
             public void onError(Objective objective, ObjectiveError error) {
+                this.error = error;
                 errorContexts.add(this);
                 finish();
             }
@@ -387,7 +389,7 @@
 
             @Override
             public String toString() {
-                return String.format("(%s, %s)", deviceId, objective);
+                return String.format("(%s on %s for %s)", error, deviceId, objective);
             }
         }
     }