This error is returned when a request is made for an item that does not exist. This could be because the item has been deleted or you may not have the correct permissions to view it.
Update any direct references to items that you may be using. For example, if you’re building an AQS query, remove any references to the Item ID mentioned in the error message.
If you’re attempting to open an item from a layer, wait for the layer to rebuild (typically 1 minute) and then refresh. Any items that were recently deleted will no longer appear.