QuickBooks Error H404: Database Server Connection Lost

QuickBooks Desktop error H404 means the host Database Server Manager connection failed. This page shows how to restore and stabilize it.

QuickBooks Desktop error H404 appears when a workstation cannot reach the Database Server Manager on the host computer. The company file is usually intact. The problem is the network path between the two machines. Our engineers see this most often after a host restart, a firewall change, or a change to the host's network address. The fix is straightforward once you identify where the connection breaks.

The error message verbatim

The full message reads: "Error H404: QuickBooks cannot connect to the database server manager on the host computer." Some versions shorten it to "H404: Database Server Manager not found." In both cases, the error appears when you try to open a company file in multi-user mode. It can also appear a few minutes after you open the file, when the workstation loses the connection.

The meaning of H404

H404 is a network error, not a data corruption error. It tells us the QuickBooks client on the workstation sent a request to the host, and the host's Database Server Manager did not answer. The Database Server Manager is the component that brokers multi-user access to company files. It listens on TCP port 4242. When that port is unreachable, QuickBooks cannot verify the file location and throws H404. The file itself is usually fine.

The usual triggers

A handful of events cause H404. The most common is a host computer that was rebooted and did not restart the Database Server Manager. A close second is a firewall rule that blocks port 4242. Other triggers include a changed IP address on the host, a disabled QuickBooks hosting mode, and a workstation whose QuickBooks services have stopped. We also see it when the file is opened on the host in single-user mode, which prevents other computers from connecting.

Fixing H404 by scenario

We recommend the fixes below in order. Most H404 cases resolve with the first scenario.

Scenario 1: Database Server Manager is not running on the host

1. On the host computer, open the QuickBooks Database Server Manager. You can find it in the Windows Start menu under the QuickBooks folder.
2. If it is not running, launch it. The window shows a list of folders it scans.
3. Confirm that the folder containing your company file is listed. If not, add the folder and let the scan complete.
4. Open QuickBooks on the host and verify the company file opens in multi-user mode. Use the File menu, then Switch to Multi-user Mode.
5. From the workstation, try to open the same file again.

Scenario 2: Windows Firewall is blocking the connection

1. On the host, open Windows Defender Firewall with Advanced Security.
2. Check the inbound rules for QuickBooks. There should be rules for QuickBooks Database Server Manager and for port 4242.
3. If a rule is missing, add one that allows TCP port 4242. If the rule exists but is disabled, enable it.
4. Apply the change and test from the workstation.
5. If you run third-party security software, add the same exception there.

Scenario 3: Hosting mode is disabled or the file is not shared

1. On the host, open QuickBooks and go to File, then Utilities, then Host Multi-User Access. This enables hosting.
2. Check that the company file is in a folder the Database Server Manager scans.
3. Open the file on the host in multi-user mode.
4. On the workstation, map a drive to the host's shared folder, or use the browse window in QuickBooks to locate the file.

Scenario 4: The host's IP address or computer name changed

1. On the host, open a command prompt and run ipconfig. Note the current IPv4 address.
2. On the workstation, try to reach the host by that IP address instead of the computer name.
3. If that works, update the shortcut on the workstation to use the IP address or the current computer name.
4. For a long-term fix, assign a static IP address to the host so the address does not change again.

Preventing a recurrence

Set the QuickBooks Database Server Manager service to start automatically. In the Windows Services console, locate the service name that contains Database Server Manager and set its Startup Type to Automatic. Keep QuickBooks hosting mode enabled on the host. Assign a static IP address or a reserved DHCP lease to the host so workstations always find it at the same address. Confirm that your firewall rules for port 4242 survive security software updates. Finally, when you restart the host, wait until the Database Server Manager finishes scanning its folders before opening the file from a workstation. These steps stop H404 from coming back in nearly every case.