diff --git a/dom/workers/WorkerPrivate.cpp b/dom/workers/WorkerPrivate.cpp
index 27eb570e90..c6ef21f2cd 100644
--- a/dom/workers/WorkerPrivate.cpp
+++ b/dom/workers/WorkerPrivate.cpp
@@ -2543,6 +2543,12 @@ WorkerPrivateParent<Derived>::DisableDebugger()
 
   WorkerPrivate* self = ParentAsWorkerPrivate();
 
+  // RegisterDebugger might have been dispatched but not completed.
+  // Wait for its execution to complete before unregistering.
+  if (!NS_IsMainThread()) {
+    self->WaitForIsDebuggerRegistered(true);
+  }
+
   if (NS_FAILED(UnregisterWorkerDebugger(self))) {
     NS_WARNING("Failed to unregister worker debugger!");
   }
diff --git a/media/webrtc/signaling/src/peerconnection/PeerConnectionImpl.h b/media/webrtc/signaling/src/peerconnection/PeerConnectionImpl.h
index 1dcc70519a..6229e1c95b 100644
--- a/media/webrtc/signaling/src/peerconnection/PeerConnectionImpl.h
+++ b/media/webrtc/signaling/src/peerconnection/PeerConnectionImpl.h
@@ -530,7 +530,8 @@ public:
   void GetFingerprint(nsAString& fingerprint)
   {
     char *tmp;
-    GetFingerprint(&tmp);
+    nsresult rv = GetFingerprint(&tmp);
+    NS_ENSURE_SUCCESS_VOID(rv);
     fingerprint.AssignASCII(tmp);
     delete[] tmp;
   }
diff --git a/security/nss/lib/softoken/pkcs11.c b/security/nss/lib/softoken/pkcs11.c
index 8510064f37..ae2cdbd27e 100644
--- a/security/nss/lib/softoken/pkcs11.c
+++ b/security/nss/lib/softoken/pkcs11.c
@@ -2798,8 +2798,9 @@ sftk_CloseAllSessions(SFTKSlot *slot, PRBool logout)
             } else {
                 SKIP_AFTER_FORK(PZ_Unlock(lock));
             }
-            if (session)
-                sftk_FreeSession(session);
+            if (session) {
+                sftk_DestroySession(session);
+            }
         } while (session != NULL);
     }
     return CKR_OK;
@@ -4034,8 +4035,6 @@ NSC_CloseSession(CK_SESSION_HANDLE hSession)
     if (sftkqueue_is_queued(session, hSession, slot->head, slot->sessHashSize)) {
         sessionFound = PR_TRUE;
         sftkqueue_delete(session, hSession, slot->head, slot->sessHashSize);
-        session->refCount--; /* can't go to zero while we hold the reference */
-        PORT_Assert(session->refCount > 0);
     }
     PZ_Unlock(lock);
 
@@ -4056,6 +4055,8 @@ NSC_CloseSession(CK_SESSION_HANDLE hSession)
         if (session->info.flags & CKF_RW_SESSION) {
             (void)PR_ATOMIC_DECREMENT(&slot->rwSessionCount);
         }
+        sftk_DestroySession(session);
+        session = NULL;
     }
 
     sftk_FreeSession(session);
diff --git a/security/nss/lib/softoken/pkcs11i.h b/security/nss/lib/softoken/pkcs11i.h
index ff062f0df0..7c7fb6953b 100644
--- a/security/nss/lib/softoken/pkcs11i.h
+++ b/security/nss/lib/softoken/pkcs11i.h
@@ -285,7 +285,6 @@ struct SFTKSessionStr {
     SFTKSession *next;
     SFTKSession *prev;
     CK_SESSION_HANDLE handle;
-    int refCount;
     PZLock *objectLock;
     int objectIDCount;
     CK_SESSION_INFO info;
@@ -683,6 +682,7 @@ extern SFTKSlot *sftk_SlotFromSessionHandle(CK_SESSION_HANDLE handle);
 extern CK_SLOT_ID sftk_SlotIDFromSessionHandle(CK_SESSION_HANDLE handle);
 extern SFTKSession *sftk_SessionFromHandle(CK_SESSION_HANDLE handle);
 extern void sftk_FreeSession(SFTKSession *session);
+extern void sftk_DestroySession(SFTKSession *session);
 extern SFTKSession *sftk_NewSession(CK_SLOT_ID slotID, CK_NOTIFY notify,
                                     CK_VOID_PTR pApplication, CK_FLAGS flags);
 extern void sftk_update_state(SFTKSlot *slot, SFTKSession *session);
diff --git a/security/nss/lib/softoken/pkcs11u.c b/security/nss/lib/softoken/pkcs11u.c
index dfed660a9f..1acc52e1c2 100644
--- a/security/nss/lib/softoken/pkcs11u.c
+++ b/security/nss/lib/softoken/pkcs11u.c
@@ -1813,7 +1813,6 @@ sftk_NewSession(CK_SLOT_ID slotID, CK_NOTIFY notify, CK_VOID_PTR pApplication,
         return NULL;
 
     session->next = session->prev = NULL;
-    session->refCount = 1;
     session->enc_context = NULL;
     session->hash_context = NULL;
     session->sign_context = NULL;
@@ -1837,11 +1836,10 @@ sftk_NewSession(CK_SLOT_ID slotID, CK_NOTIFY notify, CK_VOID_PTR pApplication,
 }
 
 /* free all the data associated with a session. */
-static void
+void
 sftk_DestroySession(SFTKSession *session)
 {
     SFTKObjectList *op, *next;
-    PORT_Assert(session->refCount == 0);
 
     /* clean out the attributes */
     /* since no one is referencing us, it's safe to walk the chain
@@ -1885,31 +1883,20 @@ sftk_SessionFromHandle(CK_SESSION_HANDLE handle)
 
     PZ_Lock(lock);
     sftkqueue_find(session, handle, slot->head, slot->sessHashSize);
-    if (session)
-        session->refCount++;
     PZ_Unlock(lock);
 
     return (session);
 }
 
 /*
- * release a reference to a session handle
+ * release a reference to a session handle. This method of using SFTKSessions
+ * is deprecated, but the pattern should be retained until a future effort
+ * to refactor all SFTKSession users at once is completed.
  */
 void
 sftk_FreeSession(SFTKSession *session)
 {
-    PRBool destroy = PR_FALSE;
-    SFTKSlot *slot = sftk_SlotFromSession(session);
-    PZLock *lock = SFTK_SESSION_LOCK(slot, session->handle);
-
-    PZ_Lock(lock);
-    if (session->refCount == 1)
-        destroy = PR_TRUE;
-    session->refCount--;
-    PZ_Unlock(lock);
-
-    if (destroy)
-        sftk_DestroySession(session);
+    return;
 }
 
 void