A connection was successfully established with the server, but an error occurred during the login process.

Server=xxxx;Database=xxxx;Trusted_Connection=true;

Add the TrustServerCertificate=True

Server=xxxx;Database=xxxx;Trusted_Connection=true;TrustServerCertificate=True

(please note that Trusted_Connection=true in the example is a part of user/login settings for MS integrated security. Do not add that if you use SQL server login)

Other things that may come into play:

Integrated Security=True; Encrypt=True; TrustServerCertificate=True;

SQL connection 4.x has changed its default setting: Encrypt=True from Encrypt=False

For search: The certificate chain was issued by an authority that is not trusted