Did you know that QuickBooks error code 6123, 0 is a 6000-error series that is associated with the company file? The error appears on the screen stating: We’re sorry, but QuickBooks can’t open your company file. This error shows up when you try to open company file in multi-user mode. You can come across the QuickBooks error code 6123, when you try to open your company file directly from the network. The error can be experienced due to a handful of reasons which will be discussing later in this segment. In order to understand the QuickBooks error 6123 better, make sure to stick around the segment till the end.