Troubleshooting

Probably you use the default installed java version, gnu classpath/gjc. We recommend the Sun JVM, but JVMs of other vendors should work as well

Search for "gjc" in the errormessages:

java.lang.ArrayIndexOutOfBoundsException
   at java.lang.System.arraycopy(libgcj.so.70)
   at java.io.ObjectInputStream.read(libgcj.so.70 )
   at java.io.InputStream.skip(libgcj.so.70)
   at com.izforge.izpack.installer.Unpacker.run(Unpacker.java:425)
   at java.lang.Thread.run(libgcj.so.70)

or

12 Aug 2008 16:34:31,161 [P1-9] WARN  (ServletHandler.java
[handle]:629) - Error for /exist/logo.jpg
java.lang.NoClassDefFoundError: org.apache.cocoon.reading.ImageReader
  at java.lang.Class.initializeClass(libgcj.so.81)
  at java.lang.Class.newInstance(libgcj.so.81)

or

Exception in thread "main" java.lang.InternalError: unexpected exception
during linking: java.lang.ClassNotFoundException: javax.swing.JFrame
  at 0x004f8ca3: java.lang.Throwable.Throwable(java.lang.String)
(/usr/lib/./libgcj.so.3)
  at 0x004ebb1e: java.lang.Error.Error(java.lang.String)
(/usr/lib/./libgcj.so.3)
  at 0x004f9086:
java.lang.VirtualMachineError.VirtualMachineError(java.lang.String)
(/usr/lib/./libgcj.so.3)

ant can help you out to determine the java version:

ant -diagnostics | grep java.vm

or

build.sh diagnostics | grep java.vm

results in

java.vm.version : 1.5.0_13-119
java.vm.vendor : Apple Inc.
java.vm.name : Java HotSpot(TM) Client VM
java.vm.specification.name : Java Virtual Machine Specification
java.vm.specification.vendor : Sun Microsystems Inc.
java.vm.specification.version : 1.0
java.vm.info : mixed mode