How to Fix QuickBooks Error Code 6123, 0? 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. Read More:......See More