The user can come across an error message “The connection to the company file has been lost. QuickBooks must close immediately. Any unsaved data will need to be re-entered”. Often while working with the company file, the user might land into such error abruptly. Also, if the system turns to sleep mode, then this error could be seen. Or if the internal network card of a system is also set to go into the sleep mode after a certain period of time, then it might lead to the lost connection issue. To get rid of this QuickBooks Connection Has Been Lost error, the user can read this post carefully or can also get in touch with U.S based certified professionals, and they will guide you through the process to fix the issue.