Error -6123, 0
Connection lost to company file
High Severity
Fix Time: 15-30 minutes

Problem Overview

This error occurs when QuickBooks loses connection to the company file, typically in multi-user mode or networked environments. The connection interruption can be caused by network issues, server problems, or file access conflicts.

Common Symptoms

  • Sudden disconnection from company file
  • Unable to save transactions
  • Multi-user mode failures
  • Network timeout messages
  • Database server unresponsive

Common Causes

  • Network connectivity issues
  • QuickBooks Database Server problems
  • Firewall or antivirus blocking
  • Server overload or crashes
  • File corruption or locks

Quick Resolution

  • Restart Database Server
  • Check network connectivity
  • Verify server status
  • Update network drivers
  • Use QuickBooks File Doctor

Step-by-Step Solution

1
Restart QuickBooks Database Server
Restart the QuickBooks Database Server Manager to reset connections and clear any locks.
  1. Close QuickBooks on all workstations
  2. Press Windows Key + R, type services.msc
  3. Find QuickBooksDBXX (XX = version number)
  4. Right-click and select Restart
  5. Wait for service to fully restart
  6. Test the connection
Note: If restart doesn't work, try stopping the service completely, then starting it again.
2
Check Network Connectivity
Verify network connection between workstations and the server hosting the company file.
  1. Open Command Prompt as Administrator
  2. Type: ping [server_ip_address]
  3. Check for successful responses
  4. Test file sharing: \\[server_name]\ in Windows Explorer
  5. Verify you can access shared folders
// Example network diagnostics:
ping 192.168.1.100
tracert 192.168.1.100
net view \\SERVERNAME
3
Update Network Drivers and Settings
Outdated network drivers or incorrect settings can cause connection drops.
  1. Open Device Manager (devmgmt.msc)
  2. Expand Network adapters
  3. Right-click your network adapter → Update driver
  4. Restart computer after update
  5. Check network power management settings
Important: Disable "Allow the computer to turn off this device to save power" in network adapter properties.
4
Configure Firewall and Antivirus
Ensure firewall and antivirus aren't blocking QuickBooks network communication.
  1. Open Windows Defender Firewall
  2. Add exceptions for QuickBooks executables:
    • QBW32.EXE
    • QBDBMgrN.exe
    • QBDBMgr.exe
  3. Add port exceptions for QuickBooks (usually port 8019)
  4. Check antivirus exclusions for QuickBooks folders
5
Use QuickBooks File Doctor
The QuickBooks File Doctor can diagnose and repair network connection issues.
  1. Download and install QuickBooks Tool Hub
  2. Open Tool Hub → Company File Issues
  3. Click Run QuickBooks File Doctor
  4. Select Network Issues diagnosis
  5. Follow the repair recommendations
  6. Restart QuickBooks Database Server after repairs
Success Tip: File Doctor can automatically fix many common network and connection problems.

Network Troubleshooting Guide

Server Configuration

Ensure the server has static IP address, adequate resources (RAM, CPU), and proper QuickBooks Database Server installation. Verify server can handle multiple connections.

Security Settings

Check Windows permissions, share permissions, and security policies. Ensure all users have appropriate access rights to the company file folder.

Hardware Issues

Test network cables, switches, and routers. Check for network card errors in Device Manager. Consider network bandwidth and latency issues.

Connection Monitoring

Use network monitoring tools to identify connection drops. Check server event logs for errors. Monitor QuickBooks Database Server performance.

Network Connectivity Checklist

Frequently Asked Questions

Why does the connection drop randomly?

Random connection drops can be caused by network instability, wireless interference, server resource constraints, power management settings on network adapters, or intermittent firewall blocking. Use network monitoring tools to identify patterns in the disconnections.

Can VPN connections cause this error?

Yes, VPN connections can introduce latency and routing issues that may cause QuickBooks connection drops. Ensure the VPN has stable connectivity, adequate bandwidth, and proper routing for QuickBooks traffic. Consider using split tunneling if possible.

How many users can QuickBooks support in multi-user mode?

QuickBooks Desktop can support up to 30 simultaneous users in multi-user mode, but performance depends on server hardware, network infrastructure, and company file size. For optimal performance with 10+ users, ensure robust server hardware and gigabit network connectivity.

What if the error occurs only for specific users?

If only specific users experience connection issues, check their individual workstation network configurations, firewall settings, and user permissions. Also verify their network connectivity to the server and check for any local software conflicts (antivirus, security software).