or() must be used in the same thread that performed the TLS/SSL I/O operation, and no other OpenSSL function calls should appear in between. The current thread&#39;s error queue must be empty before the TLS/SSL I/O operation is attempted, or SSL_get_error() will not work reliably.</p>

<h1 id="NOTES">NOTES</h1>

<p>Some TLS implementations do not send a close_notify alert on shutdown.</p>

<p>On an unexpected EOF, versions before OpenSSL 3.0 returned <b>SSL_ERROR_SYSCALL</b>, nothing was added to the error 