Close a Document
ASPxSpreadsheet does not close a document when you open another document or even when you leave a page with the control. The document storage retains the document until it is hibernated and then removed from the memory after a dispose timeout. If the hibernation is disabled, the document remains in the storage until IIS process recycling occurs.
You can call the following methods to close a document explicitly:
CloseDocument(String) closes a specific document.
CloseAllDocuments() closes all open documents.
When you close a document, DocumentManager closes it for all users who work on the document. It can cause NullReferenceException and “Your session has expired” errors. To avoid these errors, close unshared documents only.