fsockopen - certificate verify failed - how to import certificate /disable the check

Hello PHP Windows community List, I'm using PHP 5.6.12 and getting the error message: Warning: fsockopen(): SSL operation failed with code 1. OpenSSL Error messages: error:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed in X:\xampp\htdocs\.... on line 320 I'm using a XAMPP portable installation. I took the cacert.pem from a subdirectory of the xampp installation (perl\vendor\lib\Mozilla\CA\cacert.pem) and copied it to X:\xampp\apache What I tried so far is adding the lines openssl.cafile="X:\xampp\apache\cacert.pem" ssl.verify_peer = false openssl.verify_peer = false to the php.ini. Restarting apache ... same error. I exported from my Firefox the self signed certificate and the corresponding root certificate as pem files and added these to the cacert.pem file. Restarted apache ... same error. WTF do I have to do to a disable the check or to use the existing certificate? I tried to increase the logging in php.ini to E_ALL with no more useful information in the log and set apache log level to debug, still no information what to do with this error. Regards Martin