FULL PRODUCT VERSION : java version "1.7.0_06" Java(TM) SE Runtime Environment (build 1.7.0_06-b24) Java HotSpot(TM) Client VM (build 23.2-b09, mixed mode, sharing) ADDITIONAL OS VERSION INFORMATION : Microsoft Windows XP [Version 5.1.2600] EXTRA RELEVANT SYSTEM CONFIGURATION : I have XP running in a VM using VMWare Fusion on OS X 10.8.1. I have smb file sharing turned on and I map a network drive from the XP to a shared directory on OS X. A DESCRIPTION OF THE PROBLEM : Using the WatchService to watch a directory in a Network Share whose Volume Serial Number is 0000-0000 causes hang. java.lang.AssertionError: Should not get here at sun.nio.fs.WindowsFileAttributes.volSerialNumber(WindowsFileAttributes.java:387) at sun.nio.fs.WindowsWatchService$Poller.implRegister(WindowsWatchService.java:361) at sun.nio.fs.AbstractPoller.processRequests(AbstractPoller.java:260) at sun.nio.fs.WindowsWatchService$Poller.run(WindowsWatchService.java:531) at java.lang.Thread.run(Thread.java:722) STEPS TO FOLLOW TO REPRODUCE THE PROBLEM : On windows map a network drive to a smb share from os x. Create a Directory Watcher (��java.nio.file.WatchService ) for a directory on the mapped drive. Error occurs EXPECTED VERSUS ACTUAL BEHAVIOR : EXPECTED - The directory watcher should handle this error better - probably should check the directory when the directory tries to register itself vs the error coming from the poll thread. ACTUAL - java.lang.AssertionError: Should not get here at sun.nio.fs.WindowsFileAttributes.volSerialNumber(WindowsFileAttributes.java:387) at sun.nio.fs.WindowsWatchService$Poller.implRegister(WindowsWatchService.java:361) at sun.nio.fs.AbstractPoller.processRequests(AbstractPoller.java:260) at sun.nio.fs.WindowsWatchService$Poller.run(WindowsWatchService.java:531) at java.lang.Thread.run(Thread.java:722) ERROR MESSAGES/STACK TRACES THAT OCCUR : java.lang.AssertionError: Should not get here at sun.nio.fs.WindowsFileAttributes.volSerialNumber(WindowsFileAttributes.java:387) at sun.nio.fs.WindowsWatchService$Poller.implRegister(WindowsWatchService.java:361) at sun.nio.fs.AbstractPoller.processRequests(AbstractPoller.java:260) at sun.nio.fs.WindowsWatchService$Poller.run(WindowsWatchService.java:531) at java.lang.Thread.run(Thread.java:722) REPRODUCIBILITY : This bug can be reproduced always.