ssl - Paypal IPN certificate Invalid -


i have been facing issue paypal ipn since last couple of days had similar problem before got resolved of post paypal ipn: certificate verify failed

curl error: [60] ssl certificate problem, verify ca cert ok. details:error:14090086:ssl routines:ssl3_get_server_certificate:certificate verify failed 

it worked fine till couple of days , started breaking flow

i tried setting curl_setopt($ch, curlopt_sslversion, 1); didnt helped

any ideas possible cause ?