diff --git a/dom/apps/src/Webapps.jsm b/dom/apps/src/Webapps.jsm
index df0d05f20e78..877ab1ff237c 100755
--- a/dom/apps/src/Webapps.jsm
+++ b/dom/apps/src/Webapps.jsm
@@ -1316,6 +1316,12 @@ this.DOMApplicationRegistry = {
       return;
     }
 
+    // Ensure we don't send additional errors for this download
+    app.isCanceling = true;
+
+    // Ensure this app can be downloaded again after canceling
+    app.downloading = false;
+
     this._saveApps().then(() => {
       this.broadcastMessage("Webapps:UpdateState", {
         app: {
@@ -1339,6 +1345,7 @@ this.DOMApplicationRegistry = {
 
     let id = this._appIdForManifestURL(aManifestURL);
     let app = this.webapps[id];
+
     if (!app) {
       debug("startDownload: No app found for " + aManifestURL);
       throw new Error("NO_SUCH_APP");
@@ -2770,6 +2777,14 @@ this.DOMApplicationRegistry = {
       // initialize the progress to 0 right now
       oldApp.progress = 0;
 
+      // Save the current state of the app to handle cases where we may be
+      // retrying a past download.
+      yield DOMApplicationRegistry._saveApps();
+      DOMApplicationRegistry.broadcastMessage("Webapps:UpdateState", {
+        app: oldApp,
+        manifestURL: aNewApp.manifestURL
+      });
+
       let zipFile = yield this._getPackage(requestChannel, id, oldApp, aNewApp);
       let hash = yield this._computeFileHash(zipFile.path);
 
@@ -4083,6 +4098,15 @@ AppcacheObserver.prototype = {
     let setError = function appObs_setError(aError) {
       debug("Offlinecache setError to " + aError);
       app.downloading = false;
+      mustSave = true;
+
+      // If we are canceling the download, we already send a DOWNLOAD_CANCELED
+      // error.
+      if (app.isCanceling) {
+        delete app.isCanceling;
+        return;
+      }
+
       DOMApplicationRegistry.broadcastMessage("Webapps:UpdateState", {
         app: app,
         error: aError,
@@ -4092,7 +4116,6 @@ AppcacheObserver.prototype = {
         eventType: "downloaderror",
         manifestURL: app.manifestURL
       });
-      mustSave = true;
     }
 
     switch (aState) {