SharePoint Online - list view threshold

Hello, guys,

I am trying to create new document set or folder in SharePoint online library. In the library there are 20,000 records. When i try to add new docoument set or folder i am getting the following message:

"The attempted operation is prohibited because it exceeds the list view threshold enforced by the administrator."

With following code:

            ListItemCreationInformation info = new    ListItemCreationInformation();
            info.UnderlyingObjectType = FileSystemObjectType.Folder;
            info.LeafName = folderName.Trim();
            ListItem newItem = documentLibrary.AddItem(info);
            newItem["Title"] = folderName;
            newItem.Update();
            web.Context.ExecuteQuery();

What is super strange is that the folder is actualy created. Is there any other way to create new item in SharePoint Online list without getting this exception?

Thank you in advance!

Jordan