Question: I connected with VPN to setup the inventory API to get product list and it works fine. Once I get the result from the web-service and i bind to UI. And also I integrated PayPal with my application for make Express checkout when I make a call for payment I'm facing this error. I use servlet for back-end process. Can any one say how to fix this issue?

```
javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: 
PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException:
unable to find valid certification path to requested target

```

Answer: 
First, you need to obtain the public certificate from the server you're trying to connect to. That can be done in a variety of ways, such as contacting the server admin and asking for it, [using OpenSSL to download it](http://www.madboa.com/geek/openssl/#cert-retrieve), or, since this appears to be an HTTP server, connecting to it with any browser, viewing the page's security info, and saving a copy of the certificate. (Google should be able to tell you exactly what to do for your specific browser.)

Now that you have the certificate saved in a file, you need to add it to your JVM's trust store. At `$JAVA_HOME/jre/lib/security/` for JREs or `$JAVA_HOME/lib/security` for JDKs, there's a file named `cacerts`, which comes with Java and contains the public certificates of the well-known Certifying Authorities. To import the new cert, run keytool as a user who has permission to write to cacerts:

```
keytool -import -file <the cert file> -alias <some meaningful name> -keystore <path to cacerts file>

```

It will most likely ask you for a password. The default password as shipped with Java is `changeit`. Almost nobody changes it. After you complete these relatively simple steps, you'll be communicating securely and with the assurance that you're talking to the right server and only the right server (as long as they don't lose their private key).
SSLHandshakeException can be resolved 2 ways.

1. Incorporating SSL 

	* Get the SSL (by asking the source system administrator, can also
	be downloaded by openssl command, or any browsers downloads the
	certificates)
	* Add the certificate into truststore (cacerts) located at
	JRE/lib/security
	* provide the truststore location in vm arguments as
	"-Djavax.net.ssl.trustStore="
2. Ignoring SSL

For this #2, please visit my other answer on another stackoverflow website:
[How to ingore SSL verification](https://stackoverflow.com/questions/12060250/ignore-ssl-certificate-errors-with-java/42823950#42823950) [Ignore SSL Certificate Errors with Java](https://stackoverflow.com/questions/12060250/ignore-ssl-certificate-errors-with-java/42823950#42823950)