This is a fix that worked for me when having this error:
[Composer\Downloader\TransportException]
The "https://getcomposer.org/version" file could not be downloaded: SSL operation failed with code 1. OpenSSL Error messages:
error:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed
Failed to enable crypto
failed to open stream: operation failed
cd /etc/ssl/certs
sudo wget https://raw.githubusercontent.com/bagder/ca-bundle/master/ca-bundle.crt
Goto php.ini and put in this:
curl.cainfo=/etc/ssl/certs/ca-bundle.crt
openssl.cafile=/etc/ssl/certs/ca-bundle.crt
Now php composer.phar self-udpate should work again.