PKIX path building failed
Recently this error message started showing up in one of our log files and needless to say was causing a few issues:
[org.apache.commons.httpclient.HttpMethodDirector] -
Turns out the process had been running long enough that while trying to perform an HTTPS based operation the certificate in the JVM for the certificate authority the target site was using had expired. A quick update of the cacerts file and everything was happy again. Yet another software rot angle to keep in mind.