Java 7 prevents FTP transfers on Windows Vista and 7 if firewall is on. Any ideas?

The problem is caused by the stateful FTP filter of the firewall. As a workaround you can disable it by executing netsh advfirewall set global StatefulFTP disable with administrator rights.

Another workaround is to start the JVM with:

-Djava.net.preferIPv4Stack=true

We tested the Windows hotfix http://support.microsoft.com/kb/2754804 and confirmed that it did resolve the problem.

I've submitted a bug report to Oracle, see bugs.sun.com/bugdatabase/view_bug.do?bug_id=7077696

They've marked the priority as low, which makes me think that they don't quite understand the magnitude of the problem, i.e. that FTP is broken on Java/Windows. I forgot to state that explicitly in the bug report. If anyone else feels like it should have a higher priority please add a comment to the Oracle bug report.

I just noticed that you can also 'vote' for the bug, so please give it a vote if you agree it's significant.