diff --git a/dom/activities/ActivitiesService.jsm b/dom/activities/ActivitiesService.jsm
index 7250523dba7..8632b6de77d 100644
--- a/dom/activities/ActivitiesService.jsm
+++ b/dom/activities/ActivitiesService.jsm
@@ -67,15 +67,18 @@ ActivitiesDb.prototype = {
 
     let self = this;
 
+    /**
+     * WARNING!! Before upgrading the Activities DB take into account that an
+     * OTA unregisters all the activities and reinstalls them during the first
+     * run process. Check Bug 1193503.
+     */
+
     function upgrade(currentVersion) {
       let next = upgrade.bind(self, currentVersion + 1);
       switch (currentVersion) {
         case 0:
           self.createSchema(aDb, next);
           break;
-        case 1:
-          self.upgradeSchemaVersion2(aDb, aTransaction, next);
-          break;
       }
     }
 
@@ -94,47 +97,6 @@ ActivitiesDb.prototype = {
     aNext();
   },
 
-  upgradeSchemaVersion2: function(aDb, aTransaction, aNext) {
-    debug("Upgrading DB to version 2");
-
-    // In order to be able to have multiple activities with same name
-    // but different descriptions, we need to update the keypath from
-    // a hash made from {manifest, name} to a hash made from {manifest,
-    // name, description}.
-    //
-    // Unfortunately, updating the keypath is not allowed by IDB, so we
-    // need to remove and recreate the activities object store.
-
-    let activities = [];
-    let objectStore = aTransaction.objectStore(STORE_NAME);
-    objectStore.openCursor().onsuccess = (event) => {
-      let cursor = event.target.result;
-      if (!cursor) {
-        aDb.deleteObjectStore(STORE_NAME);
-
-        let objectStore = aDb.createObjectStore(STORE_NAME, { keyPath: "id" });
-
-        // indexes
-        objectStore.createIndex("name", "name", { unique: false });
-        objectStore.createIndex("manifest", "manifest", { unique: false });
-
-        this.add(activities, () => {
-          debug("DB upgraded to version 2");
-          aNext();
-        }, () => {
-          dump("Error upgrading DB to version 2 " + error + "\n");
-        });
-        return;
-      }
-
-      let activity = cursor.value;
-      debug("Upgrading activity " + JSON.stringify(activity));
-      activity.id = this.createId(activity);
-      activities.push(activity);
-      cursor.continue();
-    };
-  },
-
   // unique ids made of (uri, action)
   createId: function actdb_createId(aObject) {
     let converter = Cc["@mozilla.org/intl/scriptableunicodeconverter"]