Sentinel License Manager fails to start because TCP port 1947 is already in use

If Sentinel License Manager does not start, or if Sentinel Runtime installation fails, the most common cause is that TCP port 1947 is already being used by another process.

Symptoms

• Sentinel License Manager fails to start.
• Sentinel Runtime installation does not complete successfully.
• The Sentinel Admin Control Center cannot be opened locally.
• Windows logs report that TCP port 1947 could not be opened because it is already in use.

Cause

Sentinel LDK requires TCP port 1947 for the licensing service. If another application or Windows service is already listening on that port, the Sentinel License Manager service cannot start.

Resolution

1. Uninstall the current Sentinel Runtime.
2. Confirm that the Sentinel License Manager service is no longer present or running.
3. Check whether TCP port 1947 is in use.
4. Identify the process ID associated with that port.
5. Determine which application or Windows service owns that process.
6. If the port is occupied by the Windows IP Helper service, stop the iphlpsvc service.
7. Verify that TCP port 1947 is no longer in a listening state.
8. Reinstall Sentinel Runtime 9.13 or the version recommended for your setup.
9. Verify that the Sentinel License Manager service starts normally.
10. Confirm that the local Sentinel Admin Control Center is accessible on port 1947 .

Example error

Failed to open server TCP port 1947. Maybe LM is already running (syserr 10048 / WSAEADDRINUSE).

Notes

In one confirmed case, TCP port 1947 was being used by svchost.exe hosting the Windows IP Helper service. Once that service was stopped and the port was released, Sentinel Runtime installed successfully and the licensing service started normally.