javax.net.ssl.SSLHandshakeException for 5.6.0

Hello I getting below error for soap UI open source 5.6.0 version

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

but its working fine for soap UI open source 5.5.0 version

is anyone facing same issue?