QuickBooks Error -6073, -99001 -- Multi-User File Access and Hosting Conflicts

Error -6073, -99001 blocks opening a company file in multi-user mode; our engineers walk through resolving hosting conflicts and file locks to restore access.

QuickBooks Error -6073, -99001 appears when a user attempts to open a company file in multi-user mode but QuickBooks cannot obtain the access it needs. The error indicates that another process—another workstation, a background service, or a hosting misconfiguration—has the file locked or is competing for control of it. In most cases the file itself is undamaged; the problem is environmental and can be resolved by correcting how QuickBooks and Windows interact across the network.

What the Error Message Says

The full message typically reads:

QuickBooks is attempting to open this company file: [filename]. Before you can open the company file from your computer you must open it once on the computer where the company file is located. (-6073, -99001)

In some configurations the message may also reference a connection failure or state that the file is in use and cannot be opened at this time.

What the Code Means

The -6073 component signals that QuickBooks sees a file-access conflict at the network or hosting layer. The -99001 companion code narrows the cause: another application or QuickBooks instance is holding the file open in a mode that prevents shared access. Together, these codes tell our engineers that the database manager on the server or host machine is either not running correctly, is being overridden by another workstation's hosting setting, or a non-QuickBooks process has the file locked.

What Triggers It

The most common triggers, in order of frequency we see in support cases:

1. Hosting is enabled on a workstation instead of only on the server. When more than one machine has hosting turned on, they compete for file control.
2. The file is open in Single-User mode on another machine. A user left the file open overnight or a remote session is still active.
3. Another application is locking the file. Backup software, antivirus scanners, sync tools, or a second accounting program may have the .qbw or .nd file open.
4. The QuickBooks Database Server Manager is not running or has not scanned the folder. Without the service active and configured, QuickBooks falls back to direct file access, which conflicts with multi-user mode.
5. Folder permissions or Windows firewall rules are blocking the connection. The host machine is reachable but QuickBooks ports are filtered.

How to Fix It

Scenario 1: Hosting Is Enabled on Multiple Workstations

1. On every workstation that accesses the file, open QuickBooks and go to File > Utilities.
2. Look at the menu items. If you see Stop Hosting Multi-User Access, hosting is ON—click it to turn it off.
3. If you see Host Multi-User Access, hosting is already off; leave it alone.
4. Repeat this on every workstation. Only the server or designated host machine should have hosting enabled.
5. On the host machine, confirm hosting is ON by verifying that Stop Hosting Multi-User Access appears under File > Utilities.

Scenario 2: The File Is Open on Another Machine

1. Check every computer that has access to the file, including any remote desktop sessions.
2. If QuickBooks is open with the company file loaded, close QuickBooks on that machine.
3. Wait approximately 30 seconds for the file lock to release at the Windows level.
4. Reopen the file from the workstation where the error occurred.

Scenario 3: Another Application Is Locking the File

1. On the host machine, open Task Manager and look for backup software, cloud sync clients, or antivirus processes that may be scanning the company file folder.
2. Temporarily disable or exclude the QuickBooks company file folder from backup, sync, and antivirus scanning schedules.
3. Restart the host machine to clear any residual file handles.
4. Attempt to open the file again.

Scenario 4: QuickBooks Database Server Manager Needs to Rescan

1. On the host machine, open QuickBooks Database Server Manager from the Start menu.
2. Go to the Folders tab and click Add Folder.
3. Browse to the folder containing the company file and click OK.
4. Click Scan and wait for the process to complete.
5. Verify the company file appears in the scan results with a green checkmark.
6. Open the file from a workstation in multi-user mode.

Scenario 5: Folder Permissions or Firewall Rules

1. On the host machine, right-click the company file folder and select Properties > Security.
2. Ensure the Windows user account for each workstation has Full Control or at minimum Modify and Write permissions.
3. If using a domain, confirm the QBDataServiceUser account has full permissions on the folder.
4. Open Windows Defender Firewall and verify that QuickBooks inbound rules are enabled for the correct executable paths.
5. Restart the host and try again.

How to Prevent It Recurring

Designate a single machine as the host and document it for everyone on the network. After any Windows update or QuickBooks update, verify that hosting settings have not changed on workstations—updates occasionally reset preferences. Schedule backup and antivirus scans for after-hours windows when no one is in the file, and configure exclusions for the company file folder. Finally, run the Database Server Manager scan after any update to QuickBooks itself, since version changes can invalidate the previous scan database.