This error occurs when a user tries to establish a connection with a remote computer. The cause of this error is an interruption in the connection establishment of the software. This interruption can be caused by an antivirus, firewall, or any other network configuration error.
Protocol negotiation failed error for TeamViewer
The following methods will help you in effectively fixing the Protocol negotiation failed error in TeamViewer on Windows:
1] Flush DNS
Open Windows Command Prompt, execute the following three commands sequentially in order to flush the DNS cache: Exit the Command Prompt and check if that fixes your issue. You can try to reset Winsock & reset TCP/IP as well.
2] Configure the Windows Firewall accordingly
You will have to allow TeamViewer in the Windows Firewall settings. Open Control Panel and visit the following location: Now, click on Change Settings. From the list, locate TeamViewer and check both Private and Public connection for it. Click on OK. This should fix your issue.
3] Disable the Antivirus temporarily
Some antivirus might be hampering the proper functioning of the security key. We recommend you to turn the Antivirus solution or Windows Defender off temporarily and check if that troubleshoots your issues.
4] Update TeamViewer
You need to update TeamViewer for all the users. Run TeamViewer and then click on Help in the Menu ribbon and then select Check for updates… If an update is found, you will get notified within a few seconds with pop up mini window. Select Update and follow the onscreen instructions and get the latest updates for TeamViewer installed. All the best!
