I am trying to analyse a heap dump taken from a java process that ran into memory issues. The dump was taken using jmap. I am using jhat on the dump file – I am getting java.io.IOException: Unrecognized magic number: 169897589 at com.sun.tools.hat.internal.parser.Reader.readFile(Reader.java:94) at com.sun.tools.hat.Main.main(Main.java:159) Both jdk 1.6 and 1.7 give the same error. I am running the jhat on