When debugging or testing, it may be useful to examine the raw request body. In the examples/example.php file, after your API call, use this code to echo out the status code, body, and headers:
echo $response->statusCode();
echo $response->body();
echo $response->headers();If any SSL errors occur during API calls, an InvalidRequest will be thrown. This will provide information to help debug the issue further.
If the issue is caused by an unrecognized certificate, it may be possible that PHP is unable to locate your system's CA bundle. An easy fix would be requiring the composer/ca-bundle package - this library will automatically detect and use that to locate the CA bundle, or use Mozilla's as a fallback.