Technical and software errors, like QuickBooks Error 6073, can be quite troublesome because they often get in the way of your work. Error 6073 generally occurs when the company file you want to open is already opened by another user on a different computer. Before you can access the data, you will need to log in to the host computer and switch from single-user mode to multi-user so that different people can use the file. You can call the QuickBooks customer care number and consult a trained software expert to learn how to make the switch and troubleshoot the Error 6073.