 error condition occurs. The &quot;close notify&quot; alert is sent as a warning alert. Other examples for non-fatal errors are certificate errors (&quot;certificate expired&quot;, &quot;unsupported certificate&quot;), for which a warning alert may be sent. (The sending party may however decide to send a fatal error.) The receiving side may cancel the connection on reception of a warning alert on it discretion.</p>

<p>Several alert messages must be sent as fatal alert messages as specified by the TLS RFC. 