How to solve 'Unable to connect to sync agent' in Windows?
On Windows Vista, Windows 7, 8 or 10
1. Right click on the task bar and access the task manager.
2. In the task manager window first, select the tab Services and then click Open Services.
3. Search for vBoxx Sync Service or search for your custom Sync Service name if you enabled the branding feature.
4. If you just need to the restart the service, right-click on vBoxx Sync Service (or branded name), and select restart.
Optional:
To make sure sure the vBoxx Sync always starts and is not affected by other applications you right-click on vBoxx Sync Service (or branded name). Select "Properties".
Under Startup type you can now choose "Automatic (Delayed Start)"
Note: This configuration will slow down the sync tool startup, but it will prevent any block from other apps such as anti-viruses.