Error when making PUT request from ThingWorx: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target

I am trying to use the API from a third party hosted AWS platform (ThingWorx if anyone is familiar).
I have my access token in the header and am using a PUT call (to change bulb state)

I get the following error when I execute:

Wrapped 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 Cause: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target