QuickBooks error 6123, 0 is seen at the time of upgrading a company file in QuickBooks desktop. The user might also stumble upon such an error while trying to restore a backup. Such an error is usually seen with an error message stating “Connection to the QuickBooks company file has been lost”. The user also ends up in such an error when trying to open a company file over a network in multi-user environment or when the user is upgrading a company file to a new version of QuickBooks.
When the user tries to open the company file, an error message can be seen stating “The company file you selected could not be found. You can try one of the following: Choose the ‘Open or restore company…’ command from the file menu to look for this file in a different directory” or Use the Search tool from the windows start menu to search for this file in your computer.