FLUME-1373 (Remove hardcoded file separator in HDFSEventSink ) regressed the HDFS in Windows. The fix was done per PMD/Findbugs alert. The fix was to replace '/' with the OS file separator. The problem is that the code is not trying to build a local path; it's trying to combine strings to form a URI. In Linux, OS separator is '/' and this is not a problem. In windows, OS separator is '\' and therefore you end up with paths like hdfs://foo\var. The best fix would be to use URL objects but new URL("hdfs://..") throws unknown protocol HDFS. The most cost effective fix seems to be revert to hardcoding '/'