QuickBooks Connection Diagnostic Tool is a useful tool that helps QuickBooks desktop users to fix an assortment of issues related to multiple network and company file corruptions. This robust tool finds and fixes connection errors between QuickBooks, company files and the database manager. There are multiple other uses of this diagnostic tool as well such as many common networking and multi-user errors that include H series errors, 6000 series errors and others that show up while opening a company file.