I was attempting to get the ShowFileHandler to show a .png file, and it was failing. But in non-ZK mode it worked just fine! It took a while, but it seems that we upload to zk as a text, and download as well. I've attached a unit test that demonstrates the problem, and a fix. You have to have a binary file in the conf directory to make the test work, I put solr.png in the collection1/conf/velocity directory.