I'm getting above exception for this line:
SolrClient client = new HttpSolrClient("<host>");
Adding commons-logging-1.2.jar as suggested here didn't change anything; nor did adding commons-codec-1.10.jar suggested here.
My app is a JSF web application deployed in Glassfish 4.0 .
I was only adding the jars locally in the NetBeans IDE. Once I added them as dependencies in the maven file instead, all is good.