When restoring a company file from Quickbooks, users often encounter the QuickBooks error code 6123. When this error occurs, the company file cannot be accessed. If you attempt to open company files from a multi-user network, you may experience the exact same problem. Additionally, a "Problem Connecting to Server" message will appear if the file is opened directly from the network.
Solution #1 Use QuickBooks File Doctor tool
QuickBooks File Doctor is an excellent tool to fix some of the most common causes that trigger QuickBooks errors.
You can download this handy tool from here.
Once the QBFD tool is downloaded, install it and run on your system.
It will display you the possible damages in data or company file that may be causing this error 6123.
You will have two options to fix the damages shown in the result you received after running the tool:
You can restore the backup of company files.
If you are not able to open your company file, send your company file to QuickBooks data recovery Team.
Solution #2 Install and run QuickBooks Connection Diagnostic Tool
On your host (main) computer, check my network connection. Install and run the QuickBooks Connection Diagnostic Tool.
Move to the next solution if the above mentioned solutions dont work for you.
Solution #3 Fix damaged Data files
If theError Code -6123, 0 still exists after trying solution 1 and 2, follow the following steps to fix the network data file.
Press the Windows key (Start button) and click Explore.
Check your Company file and right click the file with .ND extension.
Rename it to .ndold
To switch to multiple user mode you can do the following:
Go to File menu.
Then Select Utilities
Host multi-user access.
Go to File>Switch to Multi-user mode