Could not establish a secure connection to the server

[Mark Qian]

The odd thing is that it shows that verification successfully using "ssl check"

$ knife ssl check
Connecting to host chefserver.example.com:443
Successfully verified certificates from `chefserver.example.com'

But when I run "client list" I got

$ knife client list
ERROR: SSL Validation failure connecting to host: chefserver.example.com - SSL_connect SYSCALL returned=5 errno=0 state=SSLv2/v3 read server hello A
ERROR: Could not establish a secure connection to the server.
Use knife ssl check to troubleshoot your SSL configuration.
If your Chef Server uses a self-signed certificate, you can use
knife ssl fetch to make knife trust the server's certificates.

Original Exception: OpenSSL::SSL::SSLError: SSL_connect SYSCALL returned=5 errno=0 state=SSLv2/v3 read server hello A

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I can telnet to the server 443 without problem so proxy should not be an issue.

I used Chef Version: 12.3.0 in Ubuntu 14.04

I also added the following content to /etc/opscode/chef-server.rb and /var/opt/opscode/chef-server.rb

ginx['url'] = "https://chefserver"
nginx['server_name'] = "chefserver"
nginx['ssl_certificate'] = "/var/opt/opscode/nginx/ca/chefserver.crt"
nginx['ssl_certificate_key'] = "/var/opt/opscode/nginx/ca/chefserver.key"

It did not help: still got the same error

Any suggestion?

thanks