diff --git a/Notesnook.API/Hubs/SyncV2Hub.cs b/Notesnook.API/Hubs/SyncV2Hub.cs
index 2db1eba..6e05255 100644
--- a/Notesnook.API/Hubs/SyncV2Hub.cs
+++ b/Notesnook.API/Hubs/SyncV2Hub.cs
@@ -80,21 +80,21 @@ namespace Notesnook.API.Hubs
             await base.OnConnectedAsync();
         }
 
-        private Action<SyncItem, string, long> MapTypeToUpsertAction(string type)
+        private Action<IEnumerable<SyncItem>, string, long> MapTypeToUpsertAction(string type)
         {
             return type switch
             {
-                "settingitem" => Repositories.Settings.Upsert,
-                "attachment" => Repositories.Attachments.Upsert,
-                "note" => Repositories.Notes.Upsert,
-                "notebook" => Repositories.Notebooks.Upsert,
-                "content" => Repositories.Contents.Upsert,
-                "shortcut" => Repositories.Shortcuts.Upsert,
-                "reminder" => Repositories.Reminders.Upsert,
-                "relation" => Repositories.Relations.Upsert,
-                "color" => Repositories.Colors.Upsert,
-                "vault" => Repositories.Vaults.Upsert,
-                "tag" => Repositories.Tags.Upsert,
+                "settingitem" => Repositories.Settings.UpsertMany,
+                "attachment" => Repositories.Attachments.UpsertMany,
+                "note" => Repositories.Notes.UpsertMany,
+                "notebook" => Repositories.Notebooks.UpsertMany,
+                "content" => Repositories.Contents.UpsertMany,
+                "shortcut" => Repositories.Shortcuts.UpsertMany,
+                "reminder" => Repositories.Reminders.UpsertMany,
+                "relation" => Repositories.Relations.UpsertMany,
+                "color" => Repositories.Colors.UpsertMany,
+                "vault" => Repositories.Vaults.UpsertMany,
+                "tag" => Repositories.Tags.UpsertMany,
                 _ => null,
             };
         }
diff --git a/Notesnook.API/Repositories/SyncItemsRepository.cs b/Notesnook.API/Repositories/SyncItemsRepository.cs
index 73b2c60..ecdce27 100644
--- a/Notesnook.API/Repositories/SyncItemsRepository.cs
+++ b/Notesnook.API/Repositories/SyncItemsRepository.cs
@@ -130,8 +130,45 @@ namespace Notesnook.API.Repositories
             );
 
             dbContext.AddCommand((handle, ct) => Collection.ReplaceOneAsync(handle, filter, item, new ReplaceOptions { IsUpsert = true }, ct));
-            // await base.UpsertAsync(item, (x) => (x.ItemId == item.ItemId) && x.UserId == userId);
-            base.Upsert(item, (x) => x.UserId == userId && x.ItemId == item.ItemId);
+        }
+
+        public void UpsertMany(IEnumerable<SyncItem> items, string userId, long dateSynced)
+        {
+            var userIdFilter = Builders<SyncItem>.Filter.Eq("UserId", userId);
+            var writes = new List<WriteModel<SyncItem>>();
+            foreach (var item in items)
+            {
+                if (item.Length > 15 * 1024 * 1024)
+                {
+                    throw new Exception($"Size of item \"{item.ItemId}\" is too large. Maximum allowed size is 15 MB.");
+                }
+
+                if (!IsValidAlgorithm(item.Algorithm))
+                {
+                    throw new Exception($"Invalid alg identifier {item.Algorithm}");
+                }
+
+                // Handle case where the cipher is corrupted.
+                if (!IsBase64String(item.Cipher))
+                {
+                    Slogger<SyncHub>.Error("Upsert", "Corrupted", item.ItemId, item.Length.ToString(), item.Cipher);
+                    throw new Exception($"Corrupted item \"{item.ItemId}\" in collection \"{this.collectionName}\". Please report this error to support@streetwriters.co.");
+                }
+
+                var filter = Builders<SyncItem>.Filter.And(
+                    userIdFilter,
+                    Builders<SyncItem>.Filter.Eq("ItemId", item.ItemId)
+                );
+
+                item.DateSynced = dateSynced;
+                item.UserId = userId;
+
+                writes.Add(new ReplaceOneModel<SyncItem>(filter, item)
+                {
+                    IsUpsert = true
+                });
+            }
+            dbContext.AddCommand((handle, ct) => Collection.BulkWriteAsync(handle, writes, options: new BulkWriteOptions { IsOrdered = false }, ct));
         }
 
         private static bool IsBase64String(string value)