Quickbooks Connection Has Been Lost error occurs due to some problem while setting up the network connection. It may occur due to damaged or corrupted files QBWUSER.INI are corrupted or damaged. This damaged file can cause a workstation crash or it will affect the workflow. You will feel some lag. The user is also not able to work comfortably whenever this error occurs. It can block access to the file of the company for the user. User entered data can be lost while entering the data. The message that appeared is: