getAccessToken function in V3 api is not working in my server.I created the authorization code and then call the functiongetAccessToken ($redirectURI, $clientId, $clientSecret, $code).
In local (localhost) it is working and I got the access token. But in server the function gives boolean false.
SSL certificate problem: unable to get local issuer certificate
Note: Both local machine and server are php 7
Thank you for reaching out to Constant Contact's API Support.
Our v3 API requires TLS 1.2 so this error indicates that your website is not using the correct level of security.