SSL: use of the SSL_OP_IGNORE_UNEXPECTED_EOF option. A new behaviour was introduced in OpenSSL 1.1.1e, when a peer does not send close_notify before closing the connection. Previously, it was to return SSL_ERROR_SYSCALL with errno 0, known since at least OpenSSL 0.9.7, and is handled gracefully in nginx. Now it returns SSL_ERROR_SSL with a distinct reason SSL_R_UNEXPECTED_EOF_WHILE_READING ("unexpected eof while reading"). This leads to critical errors seen in nginx within various routines such as SSL_do_handshake(), SSL_read(), SSL_shutdown(). The behaviour was restored in OpenSSL 1.1.1f, but presents in OpenSSL 3.0 by default. Use of the SSL_OP_IGNORE_UNEXPECTED_EOF option added in OpenSSL 3.0 allows to set a compatible behaviour to return SSL_ERROR_ZERO_RETURN: https://git.openssl.org/?p=openssl.git;a=commitdiff;h=09b90e0 See for additional details: https://github.com/openssl/openssl/issues/11381