SSL routines:ssl3_read_bytes:ssl/tls alert handshake failure

OpenSSL 3.3 and later print "ssl/tls alert handshake failure", earlier versions "sslv3 alert handshake failure" (same code 0A000410; 1.1.1 used 14094410). The line ends with the source location and "SSL alert number 40".

OpenSSL (client side) — TLS alert 40 (handshake_failure) received from the server

What it means

The server sent TLS alert 40 (handshake_failure) and closed the connection. It is a generic refusal: the server found no acceptable cipher suite, key-exchange group or signature algorithm in the ClientHello, required a client certificate, or rejected the requested server name. The client cannot learn the reason from the alert; the server's log has it.

Why it happens

• No common cipher suite

  common

  Legacy servers limited to RSA key exchange, 3DES or RC4 suites; or strict servers allowing a handful of suites an old client lacks.

• A client certificate is required (TLS 1.2)

  common

  With TLS 1.2, many servers answer a missing or unacceptable client certificate with handshake_failure; TLS 1.3 servers use certificate_required (alert 116) instead.

• Missing or unknown SNI

  occasional

  openssl s_client sends SNI only when the host is a name or -servername is given; CDNs and multi-tenant proxies abort handshakes without a known name.

• No common group or signature algorithm

  rare

  Servers restricted to a single group (for example a post-quantum hybrid) or to RSA-PSS signatures can fail against clients that offer neither.

How to fix it

1. 1.

   Read the server's log

   The server records the actual reason, e.g. "no shared cipher" or "peer did not return a certificate".

   # The server knows why; with openssl s_server or nginx the log says e.g.
   #   ...:tls_post_process_client_hello:no shared cipher
   #   ...:tls_process_client_certificate:peer did not return a certificate
   sudo tail -n 50 /var/log/nginx/error.log | grep -i ssl

2. 2.

   Narrow it down from the client

   Vary SNI, the protocol version, the cipher list and the presence of a client certificate; the variant that succeeds identifies the missing piece.

   h=api.example.com
   echo | openssl s_client -connect $h:443 -servername $h -brief                       # with SNI
   echo | openssl s_client -connect $h:443 -servername $h -tls1_2 -cipher 'ALL:@SECLEVEL=0' -brief
   echo | openssl s_client -connect $h:443 -servername $h -cert client.pem -key client.key -brief   # mTLS

3. 3.

   Server owners: offer current suites

   TLS 1.3 plus TLS 1.2 with ECDHE and AEAD suites works with every maintained client.

   # nginx: modern suites for TLS 1.2 plus TLS 1.3
   ssl_protocols TLSv1.2 TLSv1.3;
   ssl_ciphers ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384;

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