IBM Support

Cannot find a free socket for the debugger error debugging Java on Windows Vista

Technote (troubleshooting)


This technote explains why attempts to debug a stand-alone Java™ program in IBM® Rational Application Developer v7 (v7.0 through to v7.0.0.5) on Windows Vista™ results in the error Cannot find a free socket for the debugger.


The problem may occur if you are using RAD or an older version.

This is a known problem with IBM JDK 1.5 SR4 on Windows Vista, which is used to launch RAD workspaces. The bug in IBM JDK 1.5 SR4 when running on Windows Vista will cause the Java debugger in RAD not able to find a free TCP/IP socket.

Resolving the problem

Update to IBM JDK used by RAD to 1.5 SR5 or above.

Since RAD is released with an updated IBM JDK 1.5 SR6, a simple way to resolve this issue is by updating RAD to

Cross Reference information
Segment Product Component Platform Version Edition
Software Development Rational Software Architect Windows 7.0,,,,, Edition Independent

Document information

More support for: Rational Application Developer for WebSphere Software
Debugging Applications

Software version: 7.0,,,,,

Operating system(s): Windows

Reference #: 1303383

Modified date: 23 November 2010