The problem :
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curl_exec error 60 SSL certificate problem
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This is mainly caused because the curl root certificates file does not contain the particular root certificate chain.The best method would be add the correct root certificate to the file obtained by running the command
curl-config --ca
or a quick dirty trick would be add the following line
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curl_setopt( $ch, CURLOPT_SSL_VERIFYPEER, 0 );
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to the file /usr/lib/php/SOAP/Transport/HTTP.php
in function _sendHTTPS
Just after the line
$ch = curl_init();
