Error logging and troubleshooting on Windows


You can use synxfpng with the -s option to troubleshoot License Manager network connection problems. See synxfpng utility for details.

You can use lmcheck to troubleshoot Synergy License Web Service connection problems. See lmcheck utility.


Because License Manager server uses TCP/IP to communicate, you may experience TCP/IP errors. See Network requirements (TCP/IP) for client/server products for more information about TCP/IP.

Error logging

By default, the License Manager service, synlm, always logs its version, start-up and shut-down messages, and any errors it encounters to the Windows application event log. Use the Windows Event Viewer to view the log.

You can request more verbose logging in a separate log file. Verbose logging includes additional information such as licensing activity (logins and logouts) and the session and seat IDs. You can run lmu -s to see these IDs, so that you can match them up with the logging output.


Synd buffers the logging information and then periodically writes it to the log, so unless there is a lot of licensing activity, you may not see anything in the log right away. You can force synd to write to the log by stopping the service. See Stopping License Manager server.

To request verbose logging,

1. In the Synergy Configuration Program, click the Advanced button on the Licensing tab.
2. In the Advanced License Manager dialog box, select Enable verbose logging.
3. If desired, change the default log file name and location. Include the complete path. If the log file specified does not exist, it will be created, but the directory path must exist. By default, the log is named synd.log and is located in the synergyde\dbl\bin directory.
4. Click OK.

Remember to review and clear the log from time to time. Do not leave verbose logging enabled indefinitely because the file will get quite large.

Troubleshooting licensing errors

Also see Displaying polling data and status for messages (such as “Reg string not found”) that display in lmu output and in the License Synchronization pane of the Synergy Configuration Program.

Cannot access Network License Server error

The error “Cannot access Network License Server” (or sometimes just “Cannot access license server”) can occur on license clients as well as on machines with local licensing. This error may occur when running a Synergy application or when configuring the license client with lmu.

The error may be accompanied by a system error number, such as 11004 (usually on a client) or 10061 (usually on a server). There may be additional text (such as the server name that the client is attempting to connect to) that offers a clue to the problem. You may also want to check the Windows application event log for additional information.

By default, License Manager uses port 2380 to communicate. If there is a firewall (any firewall, including the built-in Windows firewall) between a license server and a license client, there will need to be a firewall exception rule for License Manager. This is the case even with local (stand-alone) licensing because the machine is, in effect, serving licenses to itself. If License Manager can’t get through your firewall, you will see a “cannot access network license server” error.

For network licensing: If there is a firewall between your license server and license clients, it needs to permit inbound access for License Manager (synd.exe).

For local licensing: For 10.1.1c and higher, a rule permitting License Manager access through Windows Firewall should be applied automatically.

To verify the rule is enabled,

1. Select Windows Firewall from the Windows Control Panel.
2. Select Advanced Settings in the left pane, and then click Inbound Rules to display the list.
3. Look for a rule named “Synergy License Server.” The port is set to “any” so that it will work even if License Manager is running on a non-default port.
4. If the rule is not there, go to a command prompt and run “lmuelevate”. Then, refresh the list of inbound rules and check again for the “Synergy License Server” rule.

If you know a firewall is not the issue, the steps below can help you troubleshoot this problem. For a license client start with step 1; for a machine with local licensing, start with step 3.

1. On the license client, run the Synergy Configuration Program. When it starts up, you’ll see an error message (“Unable to query License Manager…”). Click OK. The program will open and the server name will display on the Licensing tab.
2. If the server displayed is not the correct license server for this client, or if the port displayed is not the correct port, click the Advanced button to display the Advanced License Manager dialog box and enter the correct name/port in the Server name field. (The port is required only when the license server is not running on the default port [2380]. Append a colon, followed by the port number to the end of the server name, e.g., Tiger:5555.)

You must have administrator privileges to perform the following steps on the license server machine.

3. If the server (and port, if non-default) displayed is the correct license server for this client, attempt to start the Synergy Configuration Program on the license server machine. If synlm is either not registered or not started, it will be registered and started when SynConfig starts up, and then the license client should be able to access the server.
4. If attempting to run SynConfig results in an error (“Unable to query License Manager…”), click OK in the error dialog and then close the program.
5. Go to a command prompt and attempt to run any synd command, such as synd -h. If you see the standard operating system error for an unrecognized application or command, it means synd is no longer there.
6. Go to Control Panel > Programs and Features. Locate Synergy/DE on the list of installed programs, right-click on it, and select Change from the context menu to start the wizard. Click Next and then select Repair. This will reinstall missing files. When it finishes, start the Synergy Configuration Program on the server.
7. If you still cannot access the license server, contact Synergy/DE Developer Support for assistance.

Machine’s registration string <...> does not match stored string <...>

A registration string mismatch error can occur when the registration string found on the system is not the correct one for that system. Typically, this occurs when an image of one system has been copied to another system or when an image was restored from backup and there has been a hardware change.

This error is logged to the Windows event log.

If you get this error on a new system that needs to be licensed, see When a system is cloned.

If you get this error after restoring a backup or reinstalling Synergy, see When a backup is restored or a system is reinstalled.