Getting Error unable to find valid certification path to requested target

What version of the SDK do you have, and how are you running this? The certificates are included in src/com/dropbox/core/http/trusted-certs.crt, but this should be handled for you. I.e., a trusted-certs.raw is generated during the Maven build, and you can see where it's loaded in SSLConfig.java.

I have dropbox-core-sdk-2.0-beta-3.jar file in my class path.I need to load the correct client certificates in my jvm cacerts file. 

Immediately before calling getMetadataWithChildren(), can you add the following line:

    System.getProperties().list(System.out);

(You can also print to System.err if you prefer.)

That information might help us debug the issue.

A little more info. I'm calling this sdk from tomcat webapp on java 1.7. If I call the api's directly (calling the https://api.dropbox.com/1/metadata/auto/?locale=en_US&list=true&file_limit=25000) using httpsURLConnection from the same webapp the ssl handshake completes. So your client certificate is in the jvm cacerts file. 

But if I go through your SDK it fails with the error I gave you. I would rather use your sdk so I don't have to find all the URLs and then parse all the response json. 

Here is the properties list

-- listing properties --
java.runtime.name=Java(TM) SE Runtime Environment
java.protocol.handler.pkgs=javax.net.ssl
sun.boot.library.path=C:\Udev\Hubble\jdk\jre\bin
java.vm.version=24.51-b03
shared.loader=
java.vm.vendor=Oracle Corporation
java.vendor.url=http://java.oracle.com/
path.separator=;
java.vm.name=Java HotSpot(TM) 64-Bit Server VM
tomcat.util.buf.StringCache.byte.enabled=true
file.encoding.pkg=sun.io
user.script=
user.country=US
sun.java.launcher=SUN_STANDARD
sun.os.patch.level=Service Pack 1
tomcat.util.scan.StandardJarScanFilter.jarsToScan=log4j-core*.jar,log4j-taglib*.jar
java.vm.specification.name=Java Virtual Machine Specification
user.dir=C:\Udev\Hubble\tomcat\bin
java.runtime.version=1.7.0_51-b13
derby.system.home=C:\Udev\Hubble\Config
java.awt.graphicsenv=sun.awt.Win32GraphicsEnvironment
java.endorsed.dirs=C:\Udev\Hubble\tomcat/common/endorsed
os.arch=amd64
java.io.tmpdir=C:\Udev\Hubble\tomcat\temp
line.separator=

java.vm.specification.vendor=Oracle Corporation
user.variant=
java.naming.factory.url.pkgs=org.apache.naming
os.name=Windows 7
sun.jnu.encoding=Cp1252
java.library.path=C:\Udev\Hubble\jdk\bin;C:\Udev\Hubble...
java.specification.name=Java Platform API Specification
java.class.version=51.0
sun.management.compiler=HotSpot 64-Bit Tiered Compilers
os.version=6.1
sun.io.useCanonCaches=false
user.home=C:\Users\aaghili.MANAGEDMETHODS
user.timezone=America/Denver
catalina.useNaming=true
java.awt.printerjob=sun.awt.windows.WPrinterJob
java.specification.version=1.7
file.encoding=Cp1252
tomcat.util.scan.StandardJarScanFilter.jarsToSkip=bootstrap.jar,commons-daemon.jar,tomc...
catalina.home=C:\Udev\Hubble\tomcat
user.name=aaghili
java.class.path=C:\Udev\Hubble\tomcat/bin/bootstrap.j...
java.naming.factory.initial=org.apache.naming.java.javaURLContext...
http.maxConnections=30
package.definition=sun.,java.,org.apache.catalina.,org.a...
java.vm.specification.version=1.7
sun.arch.data.model=64
java.home=C:\Udev\Hubble\jdk\jre
sun.java.command=org.apache.catalina.startup.Bootstrap...
java.specification.vendor=Oracle Corporation
user.language=en
awt.toolkit=sun.awt.windows.WToolkit
java.vm.info=mixed mode
java.version=1.7.0_51
java.ext.dirs=C:\Udev\Hubble\jdk\jre\lib\ext;C:\Win...
sun.boot.class.path=C:\Udev\Hubble\jdk\jre\lib\resources....
java.vendor=Oracle Corporation
server.loader=
catalina.base=C:\Udev\Hubble\tomcat
file.separator=\
java.vendor.url.bug=http://bugreport.sun.com/bugreport/
common.loader="${catalina.base}/lib","${catalina.ba...
sun.cpu.endian=little
sun.io.unicode.encoding=UnicodeLittle
package.access=sun.,org.apache.catalina.,org.apache....
sun.desktop=windows
sun.cpu.isalist=amd64

Al, I wrote a short test program that makes HTTP requests to Dropbox servers using the SDK.  Can you try running it on your machine?

Link: https://www.dropbox.com/s/uex1nmzombsa0pu/cert-chain.zip

See "ReadMe.txt" for instructions on how to compile and run it.