In case your Windows profile user ID contains non UTF characters, such as éöáä and similar, please do the following on the server computer:
1. Open Synergy.
2. Click on the File menu and choose "Save the configuration as...".
3. Save the configuration to a directory without the account id, for example, C:\SynergyConfig\Synergy.sgc.
4. In the Synergy main window, click on "Use existing configuration".
5. Browse and select the recently created file.
6. Click Apply.
The Synergy application should now be able to read the configuration and start properly.
If this article didn't help, you can talk to someone on our support team (unless we sent you here, in which case please reply via the ticket you already have open).