Error during connection "The certificate chain was issued by an authority that is not trusted." (4229258)

Following error occurs during connection. 

In some cases, this occurs with a new install of Toad. 
"SQL Server Database Error: A connection was successfully established with the server, but then an error during the pre-login handshake.
(provider: SSL Provider, error: 0 - The certificate chain was issued by an authority that is not trusted.)"

In some cases, this occurs with an existing install and saved connection history list.
"SQL Server Database Error: The certificate chain was issued by an authority that is not trusted."

The same connection can be made via MS Management Studios.

This may be a conflict with the installation of .NET 4.5.

This may be a conflict between saved connection information in Toad and changed certificates for the user/network. 

WORKAROUND 1:

Exit Toad, go to the application data directory (C:\Users\<personal folder>\AppData\Roaming\Quest Software\Toad for SQL Server <version>) find and rename the Connections.xml file. 

Start Toad and manually create a new connection to your server. 

WORKAROUND 2:

Uncheck “Encrypt connection” check box in Toad's login window.

WORKAROUND 3:

When working with Toad for SQL Server please work with .NET 4.0, not .NET 4.5

Important Note: If working with Toad Data Point 3.3, there is an issue with Automation and .NET 4.0. Please refer to Knowledge Base Article 111017 for further information:

https://support.quest.com/SolutionDetail.aspx?id=SOL111017

WORKAROUND 4:

If .NET 4.5 must be used, connection to SQL Server can still be made through ODBC.

WORKAROUND 5:

1.  Open the Connection properties of the connection affected by the error.
2.  Click on the Advanced tab.
3.  Add the following parameter and value.
     Parameter Name:  TrustServerCertificate  
     Value:  True
4.  Hit ENTER. (Very important)
5.  Click on Save.
6.  Click on Connect.