warning: stream_socket_client(): unable to set private key file

Problem is pem file wasn't correct, I created pem file using http://www.raywenderlich.com/32960/apple-push-notification-services-in-ios-6-tutorial-part-1 . Creation of p12 file and with p12 creating pem file are not working for me. Correct process to create p12 and with p12 creating pem file as bellow

Once you have the certificate from Apple for your application, export your key and the apple certificate as p12 files. Here is a quick walkthrough on how to do this:

1. Click the disclosure arrow next to your certificate in Keychain Access and select the certificate and the key.
2. Right click and choose Export 2 items….
3. Choose the p12 format from the drop down and name it cert.p12.

Now convert the p12 file to a pem file:

$ openssl pkcs12 -in cert.p12 -out apple_push_notification_production.pem -nodes -clcerts

This is working for me, now I am getting a push notification.

Converting the key file to pem recommend in http://www.raywenderlich.com/32960/apple-push-notification-services-in-ios-6-tutorial-part-1 was causing problems for me.

Running

openssl pkcs12 -in keyname.p12 -out keyname.pem -nodes -clcerts

instead of the

openssl pkcs12 -nocerts -out keyname.pem -in keyname.p12

solved my issues.