When connecting to remote control another host or server via TeamViewer, the connection failed with the error message read “Protocol negotiation failed. Please try again.” On the TeamViewer host, it received the incoming connection, but the remote control session was silently dropped and was not established.

Many reasons can cause the TeamViewer’s protocol negotiation failed error to occur. To fix the issue so that the remote control via TeamViewer can connect properly, try the following resolution:

  1. Restart TeamViewer by quitting the TeamViewer app on the host, and then restart it.
  2. Restart the TeamViewer service in Services of Control Panel, especially for TeamViewer which is set to start with Windows and/or has unattended access set up.

    Restart TeamViewer Service

  3. Disable firewall, including Windows or third-party firewall.
  4. Disable IPS (Intrusion Prevention System).
  5. Disable anti-virus protection, or exclude TeamViewer folder or executable from anti-virus scanning.
  6. Uninstall and reinstall TeamViewer.