昨天我在Perl Monks上发布了这个问题，但是每个尝试过的人都成功了（请参见http://www.perlmonks.org/?node_id=909968）。然而，我使用了一个不同的URL，希望简化问题。
我正在尝试通过HTTPS连接到api.betfair.com，他们有一个有效的证书，我已经在我的浏览器中验证过。我正在运行ubuntu，并且有两个版本的Perl。系统自带的5.10.0可以工作，通过perlbrew安装的5.14.0失败了。代码如下：
use LWP::UserAgent;
use strict;
use warnings;
#$ENV{HTTPS_CA_FILE} = "/usr/share/ca-certificates/cacert.org/cacert.org.crt";
my $ua = LWP::UserAgent->new;
my $req = HTTP::Request->new(GET => 'https://api.betfair.com');
my $res = $ua->request($req);
print $res->headers_as_string;
print $res->content;
在系统Perl 5.10.0下运行，它可以正常工作，我会得到以下结果：
Date: Fri, 17 Jun 2011 08:33:04 GMT
Accept-Ranges: bytes
ETag: W/"0-1307353787000"
Content-Length: 0
Content-Type: text/html
Last-Modified: Mon, 06 Jun 2011 09:49:47 GMT
Client-Date: Fri, 17 Jun 2011 08:33:04 GMT
Client-Peer: 84.20.200.10:443
Client-Response-Num: 1
Client-SSL-Cert-Issuer: /C=US/O=VeriSign, Inc./OU=VeriSign Trust Network/OU=Terms of use at https://www.verisign.com/rpa (c)09/CN=VeriSign Class 3 Secure Server CA - G2
Client-SSL-Cert-Subject: /C=GB/ST=London/L=London/O=The Sporting Exchange Ltd/OU=IS/OU=Terms of use at www.verisign.com/rpa (c)05/CN=*.betfair.com
Client-SSL-Cipher: RC4-MD5
Set-Cookie: NSC_mc-80-qvcbqj.efgbvmu=ffffffff09208c5545525d5f4f58455e445a4a4229a0;expires=Fri, 17-Jun-2011 20:33:05 GMT;path=/;httponly
在 Perl 5.14.0 下运行，我得到以下结果：
如果我取消 HTTPS_CA_FILE 的注释并在 5.14.0 中重新运行，我会得到：
Content-Type: text/plain
Client-Date: Fri, 17 Jun 2011 08:35:09 GMT
Client-Warning: Internal response
Can't connect to api.betfair.com:443 (certificate verify failed)
LWP::Protocol::https::Socket: SSL connect attempt failed with unknown errorerror:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed at /home/martin/perl5/perlbrew/perls/perl-5.14.0/lib/site_perl/5.14.0/LWP/Protocol/http.pm line 51.
我已安装版本为20110409的Mozilla::CA。Mozilla::CA::SSL_ca_file()返回“/home/martin/perl5/perlbrew/perls/perl-5.14.0/lib/site_perl/5.14.0/Mozilla/CA/cacert.pem”，并且我可以读取它。我在Perl 5.14.0中使用LWP 6.02，在Perl 5.10.0中使用5.836。我读到设置HTTPS_DEBUG=1应该输出一些调试信息，但只有在使用Perl 5.10.0而不是5.14.0时才会这样做（对我来说）。
我不是SSL专家，但我尝试了一些我找到的东西，它们只让我更加困惑：
openssl verify -verbose -CAfile /home/martin/perl5/perlbrew/perls/perl-5.14.0/lib/site_perl/5.14.0/Mozilla/CA/cacert.pem < /dev/null
unable to load certificate
10888:error:0906D06C:PEM routines:PEM_read_bio:no start line:pem_lib.c:647:Expecting: TRUSTED CERTIFICATE
openssl s_client -CAfile /usr/local/share/perl/5.10.0/Mozilla/CA/cacert.pem -connect api.betfair.com:443 < /dev/null
CONNECTED(00000003)
depth=1 /C=US/O=VeriSign, Inc./OU=VeriSign Trust Network/OU=Terms of use at https://www.verisign.com/rpa (c)09/CN=VeriSign Class 3 Secure Server CA - G2
verify error:num=20:unable to get local issuer certificate
verify return:0
---
Certificate chain
0 s:/C=GB/ST=London/L=London/O=The Sporting Exchange Ltd/OU=IS/OU=Terms of use at www.verisign.com/rpa (c)05/CN=*.betfair.com
i:/C=US/O=VeriSign, Inc./OU=VeriSign Trust Network/OU=Terms of use at https://www.verisign.com/rpa (c)09/CN=VeriSign Class 3 Secure Server CA - G2
1 s:/C=US/O=VeriSign, Inc./OU=VeriSign Trust Network/OU=Terms of use at https://www.verisign.com/rpa (c)09/CN=VeriSign Class 3 Secure Server CA - G2
i:/C=US/O=VeriSign, Inc./OU=Class 3 Public Primary Certification Authority - G2/OU=(c) 1998 VeriSign, Inc. - For authorized use only/OU=VeriSign Trust Network
---
Server certificate
-----BEGIN CERTIFICATE-----
certificate snipped
sg==
-----END CERTIFICATE-----
subject=/C=GB/ST=London/L=London/O=The Sporting Exchange Ltd/OU=IS/OU=Terms of use at www.verisign.com/rpa (c)05/CN=*.betfair.com
issuer=/C=US/O=VeriSign, Inc./OU=VeriSign Trust Network/OU=Terms of use at https://www.verisign.com/rpa (c)09/CN=VeriSign Class 3 Secure Server CA - G2
---
No client certificate CA names sent
---
SSL handshake has read 3068 bytes and written 303 bytes
---
New, TLSv1/SSLv3, Cipher is RC4-MD5
Server public key is 1024 bit
Secure Renegotiation IS NOT supported
Compression: NONE
Expansion: NONE
SSL-Session:
Protocol : TLSv1
Cipher : RC4-MD5
Session-ID: 81802384A47AF45D2D809A2D10041A4E0B4B4DD821507569216A199ED467B207
Session-ID-ctx:
Master-Key: 50DEC11CD2FA57E9BFA95B0156905D2717A79F333A2028FCCCB0F1C32A6B35202A958CEF24D3D2332A00CDCD158B40FB
Key-Arg : None
Start Time: 1308304989
Timeout : 300 (sec)
Verify return code: 20 (unable to get local issuer certificate)
---
DONE
更新：我以为是因为我设置了PERL_UNICODE=SAL，但是取消设置并不能解决问题。
更新：版本： Linux ubuntu 10.10代号maverick openssl 0.9.80（我相信是我的ubuntu发行版最新的）