Complete Guide to Fix Error 6123 0 in QuickBooks Desktop

Complete Guide to Fix Error 6123 0 in QuickBooks Desktop

QuickBooks Error 6123 0 is a common company file error that appears when users try to open, restore, or access a QuickBooks company file over a network. The error message usually says “Connection Lost” and prevents QuickBooks Desktop from opening the file successfully.
This guide explains what Error 6123 0 is, why it occurs, and step-by-step methods to fix it permanently.

What Is QuickBooks Error 6123 0?
Error 6123 0 in QuickBooks Desktop occurs when QuickBooks cannot establish a proper connection with the company file location or database server. It is mostly seen in:

Multi-user mode
Hosted or network environments
While restoring a backup file

This error affects all major versions of QuickBooks Desktop and can occur on Windows 10 and Windows 11.

Common Causes of QuickBooks Error 6123 0
Error 6123 0 usually happens due to one or more of the following reasons:

Company file stored on a network or server
Incorrect folder permissions
Damaged or corrupted company file
Firewall or antivirus blocking QuickBooks
Database Server Manager not running
Network interruption
Restoring a backup from an external drive
Hosting enabled on multiple systems
Damaged .ND or .TLG files

Symptoms of Error 6123 0 in QuickBooks Desktop

QuickBooks unable to open company file
“Connection Lost” error message appears
QuickBooks crashes while opening file
Slow or frozen QuickBooks Desktop
Users disconnected in multi-user mode

Complete Methods to Fix Error 6123 0 in QuickBooks Desktop
Solution 1: Open Company File Locally

Copy the company file to your local system (C: drive)
Open QuickBooks Desktop
Try opening the file locally

This helps determine if the issue is network-related.

Solution 2: Restart QuickBooks Database Server Manager

Press Windows + R
Type services.msc and press Enter
Restart QuickBooksDBXX service
Restart your system and open QuickBooks again

Solution 3: Check Folder Permissions

Right-click the company file folder
Select Properties > Security
Ensure Full Control is given to all users
Apply changes and reopen QuickBooks

Solution 4: Disable Firewall & Antivirus Temporarily
Security software may block QuickBooks ports.

Temporarily disable firewall/antivirus
Try opening the company file
If fixed, add QuickBooks as an exception

Solution 5: Rename .ND and .TLG Files

Open company file folder
Locate files ending with .ND and .TLG
Rename them (add .old at the end)
Restart QuickBooks Database Server Manager

Solution 6: Restore Backup Correctly

Open QuickBooks Desktop
Go to File > Open or Restore Company
Choose Restore a backup copy
Restore the file to a local drive, not network

Solution 7: Use Verify and Rebuild Data Tool

Go to File > Utilities > Verify Data
If issues found, select Rebuild Data
Restart QuickBooks after completion

Solution 8: Update QuickBooks Desktop

Open QuickBooks
Go to Help > Update QuickBooks Desktop
Install all updates
Restart system

Outdated QuickBooks versions often cause Error 6123 0 Windows 10/11 issues.

Error 6123 0 in Multi-User Mode – Special Fix

Ensure hosting is enabled only on the server
Disable hosting on workstations
Confirm Database Server Manager is running properly
Check network stability

When Manual Fixes Don’t Work
If none of the above solutions resolve QuickBooks Error 6123 0, your company file may be severely corrupted or the network configuration may be incorrect.
In such cases, professional QuickBooks Error 6123 support is recommended to:

Repair damaged company files
Fix hosting and database issues
Prevent data loss
Restore QuickBooks safely

How to Prevent Error 6123 0 in Future

Always keep QuickBooks updated
Avoid storing company files on unstable networks
Perform regular backups
Use proper hosting configuration
Maintain correct folder permissions

Conclusion
QuickBooks Error 6123 0 in QuickBooks Desktop is a serious but fixable issue. Most cases are related to network, permissions, or database server problems. By following this complete guide step-by-step, you can resolve the error and restore access to your company file safely.
For persistent issues, expert assistance ensures a faster and risk-free solution.

QuickBooks Error 6123 – Connection Lost While Opening Company File

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QuickBooks Error 6123 occurs when users try to open a company file, restore a backup, or access data over a network and suddenly see the me...