php7.1的ssl配置是错误的，cert.pem不存在

First:

Check certificate file location which will be in default_cert_file key, you will found it in openssl_get_cert_locations() its php openssl function:
第一步：需找验证钥匙的地址，使用 php函数openssl_get_cert_locations().

$ php -r "print_r(openssl_get_cert_locations());"
[html]Array
(
    [default_cert_file] => /opt/lampp/share/openssl/cert.pem
    [default_cert_file_env] => SSL_CERT_FILE
    [default_cert_dir] => /opt/lampp/share/openssl/certs
    [default_cert_dir_env] => SSL_CERT_DIR
    [default_private_dir] => /opt/lampp/share/openssl/private
    [default_default_cert_area] => /opt/lampp/share/openssl
    [ini_cafile] =>
    [ini_capath] =>
)[/html]
Second:

Download http://curl.haxx.se/ca/cacert.pem:
第二步：下载最新的cacert.pem，从上面这个网址下。

$ wget http://curl.haxx.se/ca/cacert.pem
Third:

Copy certificate PEM file into default_cert_file location:
第三步：建立openssl到默认cert文件到连接。

$ sudo mv cacert.pem /opt/lampp/share/openssl/cert.pem
My php-cli is under XAMPP and default_cert_file maybe point to some place that is different than this.
注意:这个要跟上面第一步找到到地址一致。

Fourth：

Restart xampp:
重启xampp

$ sudo /opt/lampp/xampp restart
I hope anything after that should goes fine with you brothers.
希望你顺利解决。

路径和重启php的命令参照自己的配置修改。