--- a/dom/settings/SettingsRequestManager.jsm
+++ b/dom/settings/SettingsRequestManager.jsm
@@ -443,21 +443,21 @@ let SettingsRequestManager = {
       Services.tm.currentThread.dispatch(SettingsRequestManager.consumeTasks.bind(this), Ci.nsIThread.DISPATCH_NORMAL);
     }
   },
 
   finalizeSets: function(aTask) {
     let data = aTask.data;
     if (DEBUG) debug("Finalizing tasks for lock " + data.lockID);
     let lock = this.lockInfo[data.lockID];
-    lock.finalizing = true;
 
     if (!lock) {
       return Promise.reject({task: aTask, error: "Lock died, can't finalize"});
     }
+    lock.finalizing = true;
     if (lock._failed) {
       this.removeLock(data.lockID);
       return Promise.reject({task: aTask, error: "Lock failed a permissions check, all requests now failing."});
     }
     // If we have cleared, there is no reason to continue finalizing
     // this lock. Just resolve promise with task and move on.
     if (lock.hasCleared) {
       if (DEBUG) debug("Clear was called on lock, skipping finalize");
@@ -810,17 +810,16 @@ let SettingsRequestManager = {
       case "Settings:Run":
       case "Settings:Finalize":
         let kill_process = false;
         if (!msg.lockID) {
           Cu.reportError("Process sending request for lock that does not exist. Killing.");
           kill_process = true;
         }
         else if (!this.lockInfo[msg.lockID]) {
-          Cu.reportError("Process trying to access unknown settings lock.");
           if (DEBUG) debug("Cannot find lock ID " + msg.lockID);
           // This doesn't kill, because we can have things that file
           // finalize, then die, and we may get the observer
           // notification before we get the IPC messages.
           return;
         }
         else if (mm != this.lockInfo[msg.lockID]._mm) {
           Cu.reportError("Process trying to access settings lock from another process. Killing.");