JOSM unable to download data

I am using JOSM version 11223

I am unable to download data from OpenStreetMap, JOSM displays IO Exception

Failed to upload to or download data from ', -15.8902788,28.0537975, -15.8871264' due to a problem with transferring data.
Details(untranslated): PKIX path validation failed: check failed

How can I solve the problem.

Could it be that your computers clock is off?