# 40311: Application requires a TLS connection Identifier: `application_requires_a_tls_connection` The connection was rejected because it did not use TLS, but the application requires TLS connections. ## What you should do Connect over TLS. The application is configured to require it, so remove any `tls: false` setting from the client options, or set it to `true`. SDKs use TLS by default, so this normally means TLS was explicitly disabled. ## Why it happens The connection did not use TLS, but the application has the TLS-only setting enabled, which rejects non-TLS connections. This applies to connections using token authentication; a non-TLS connection using Basic authentication is rejected as 40103 instead. ## What you'll see The error is reported with code 40311 and HTTP status 403. The message is of the form `application requires TLS Connections; applicationId = `.