QuickBooks Error H303 -- Multi-User Hosting Configuration

Error H303 blocks multi-user access because the host machine needs additional configuration; our engineers walk through the fixes to restore shared access.

QuickBooks Error H303 appears when a workstation tries to open a company file stored on another machine and the host is not correctly configured for multi-user access. The error can also surface when QuickBooks Database Server Manager is not running, when firewall settings block the ports QuickBooks uses, or when the .ND (Network Descriptor) file that points the workstation to the host is damaged or stale. Our engineers treat H303 as a configuration error, not a data-loss event, and the company file itself is almost always intact.

What the Error Message Says

The full message typically reads:

This company file is on another computer, and QuickBooks needs some help connecting. Error code: H303

A variation may also display:

The company file is on another computer, and QuickBooks needs some help connecting.

Some users see an accompanying prompt to download the QuickBooks File Doctor or a suggestion to verify that hosting is turned on.

What the Code Means

H-series errors all relate to multi-user or network connectivity problems. H303 specifically indicates that the workstation cannot reach the host computer across the network. QuickBooks Desktop uses a file-sharing model where one machine hosts the company file and other machines connect to it. When any link in that chain — hosting mode, the Database Server Manager service, firewall ports, or the network descriptor file — is misconfigured, QuickBooks returns H303.

What Triggers It

The most common triggers, in order of frequency our engineers see:

1. Hosting is enabled on a workstation instead of only on the server. QuickBooks should have hosting turned on for exactly one machine — the one storing the file.
2. QuickBooks Database Server Manager is not installed, not running, or has not scanned the folder containing the company file.
3. Windows Firewall or third-party security software is blocking QuickBooks ports.
4. The .ND file is damaged, outdated, or pointing to a previous server name or IP address.
5. The company file folder is not shared with the correct permissions.
6. Network discovery or file and printer sharing is turned off at the Windows level.

How to Fix It

Scenario 1: Hosting Is Turned On at More Than One Machine

1. On every workstation, open QuickBooks and go to File > Utilities.
2. 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.
4. On the server or the machine that stores the company file, confirm that Host Multi-User Access is enabled.
5. Open the company file on each workstation in multi-user mode.

Scenario 2: QuickBooks Database Server Manager Has Not Scanned the Folder

1. On the host machine, close QuickBooks.
2. Open the Windows Start menu and launch QuickBooks Database Server Manager.
3. Go to the Folders tab and click Add Folder.
4. Browse to the folder that contains the company file and click OK.
5. Click Start Scan. The scan may take several minutes depending on folder size.
6. After the scan completes, open QuickBooks on a workstation and try multi-user mode again.

Scenario 3: Firewall or Security Software Is Blocking Access

1. On the host machine, open Windows Defender Firewall (or your third-party firewall console).
2. Confirm that the following executable names are allowed through:
   • QBW32.exe
   • QBDBMgrN.exe
   • QBWDatabaseServiceManager.exe
3. Verify that QuickBooks Desktop uses the correct port for your year version. Recent versions use dynamic ports assigned by the Database Server Manager. In Database Server Manager, click the Port Monitor tab to see which ports are active.
4. Add inbound and outbound rules for those ports for both TCP and UDP.
5. Restart the host machine and test access from a workstation.

Scenario 4: The .ND File Is Damaged or Outdated

1. On the host machine, navigate to the folder containing the company file.
2. Locate the file with the same name as your company file but a .ND extension (for example, CompanyFile.QBW.ND).
3. Right-click the .ND file and rename it to CompanyFile.QBW.ND.OLD.
4. Open QuickBooks Database Server Manager and rescan the folder as described in Scenario 2. This recreates a fresh .ND file.
5. Open QuickBooks on a workstation and attempt to connect.

Scenario 5: Folder Permissions or Network Discovery

1. On the host machine, right-click the folder containing the company file and select Properties > Sharing.
2. Confirm the folder is shared and that the user accounts on the workstations have Full Control or at least Read/Write access.
3. Open Control Panel > Network and Sharing Center > Advanced sharing settings and confirm that Network discovery and File and printer sharing are enabled.
4. On the workstation, press Windows + R, type \\server-name (the host computer's name), and confirm the shared folder is visible.

How to Prevent It Recurring

• Keep hosting enabled on only one machine — the server or the computer that physically stores the company file.
• After any Windows update, security software change, or network modification, verify that QuickBooks Database Server Manager is running and that firewall rules are still in place.
• Avoid changing the host computer's name or IP address without rescanning the company file folder in Database Server Manager afterward.
• If you replace the host machine or move the company file to a new location, delete the old .ND file and rescan so the network descriptor reflects the current path.