wp stmp curl err 60 (test mail not function)

Replies: 0

hi i have this err when i test mail.
i used plugin wp stmp with gmail.
Versions:
WordPress: 4.8.5
WordPress MS: No
PHP: 7.1.1
WP Mail SMTP: 1.2.5

Params:
Mailer: gmail
Constants: No
Client ID/Secret: Yes
Auth Code: Yes
Access Token: No

Server:
OpenSSL: No
PHP.allow_url_fopen: Yes
PHP.stream_socket_client(): Yes
PHP.fsockopen(): Yes
PHP.curl_version(): Yes
Apache.mod_security: No

Debug:
cURL error 60: SSL certificate problem: unable to get local issuer certificate (see http://curl.haxx.se/libcurl/c/libcurl-errors.html)
cURL error 60: SSL certificate problem: unable to get local issuer certificate (see http://curl.haxx.se/libcurl/c/libcurl-errors.html)
cURL error 60: SSL certificate problem: unable to get local issuer certificate (see http://curl.haxx.se/libcurl/c/libcurl-errors.html)
Error while sending via Gmail mailer: cURL error 60: SSL certificate problem: unable to get local issuer certificate (see http://curl.haxx.se/libcurl/c/libcurl-errors.html)
cURL error 60: SSL certificate problem: unable to get local issuer certificate (see http://curl.haxx.se/libcurl/c/libcurl-errors.html)

please your help now i work in localhost with wordpress