DS-Client service fails to start with an error like the following: "Failed to open ports(DS-User)"?

There are several scenarios when DS-Client may fail to start with an error mentioning ports:

1. Port 4403 is being used by a Windows service or another application. In order to operate, the DS-Client needs to open port 4403 for the TCP/UDP protocols on the machine where it is installed. If it fails, the DS-Client service will stop and will record the following error in the Windows Application Log: "Failed to open ports (ds-user,TCP)." DS-Client may fail to start on some Windows Operating Systems because of a port conflict between the DS-Client and some Microsoft services like WMI.

A workaround from Microsoft to resolve the port conflicts is described below:

a. Run "RegEdit".

b. Browse to "HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\TCPIP\Parameters"

c. Double click the key named "ReservedPorts", and add "4403-4403"

d. Make sure that the key value ends with one empty line by hitting the "Enter" key.

e. Click the "OK" button to save the Registry changes.

f. Restart Windows and the port conflict should not occur.

2. The 'services' file in c:\Windows\system32\drivers\etc is missing the following lines:

ds-user 4403/tcp #DS-Client administration port

ds-user 4403/udp #DS-Client administration port

ds-srvr 4401/tcp #DS-System operating port

3. Port 4403 is blocked by a firewall.

4. HKLM\System\CurrentControlSet\Services\TCPIP\Parameters\DatabasePath registry key is REG_SZ instead of REG_EXPAND_SZ MSN messenger 7.0/7.5 changed this registry key, so the path to the service file is not properly loaded. After changing the type of the registry key, DS-Client will run however if you run MSN messenger 7.0/7.5 again, it will change the key again. So please don't run MSN messenger 7.0/7.5 on the DS-Client computer.

5. The "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\DataBasePath" was pointing to the wrong location (%SystemRoot%\System32 instead of %SystemRoot%\System32\drivers\etc). Seems another third-party application might have modified the path.

DS-Client service started successfully after updated the registry with the correct path (%SystemRoot%\System32\drivers\etc)