- This message could appears when you have launched again the remote control too quickly after having finished another one, on the same remote host. Indeed, when you stop the remote control, the software take some time (a few seconds) for properly leaving the beforehand established communication between the two computers. So, before launching again a remote control, you may check in the services/process list that the "winvnc" task is not running at this tiime. If necessary you should kill this task, then relaunch the connection.
- This message could also appears when a firewall (the native Windows firewall or another one) blocks the VNC software or the port used by this sofware (default : 5900 ). Please create an exception in the firewall of the administration computer in order to accept "vncviewer.exe" and also an exception in the firewall of the remote host in order to accept "winvnc.exe". On these both computers, please also accept the TCP port used by VNC.
Read more : Windows XP firewall - Windows Vista firewall - Windows 7 / 8 / 10 firewall
- This message could also appears if a software running at the moment on the remote host or on the administration computer uses the same port than the one used by VNC (default : 5900). Please try to enter another port number (right click on the remote host , Remote control, Configurer, Connection tab). For example enter the port 5901, then try again by lauching the remote control.
- You can also try to increase the delay of synchonization with the WinVNC server (2000 milliseconds by default). This delay is the time between the request to start the "VNC Server / WinVNC" service on the remote host and the first connection attempt on this computer : "Tools" menu, "TightVNC Options", "General" tab. Enter 10000 (10 seconds) then test again the remote control.
- Finally, NetBIOS name resolution between your admin computer and the remote machine must be perfect. Please check the result of the following commands:
- ping COMPUTERNAME
- Try with the FQDN (Fully Qualified Domain Name) : ping COMPUTERNAME.MYDOMAIN.com
- Try with the IP address of the computer : ping 192.168.xxx.xxx