When the compiler terminates abnormally, either because a particular kind of message was issued or an exception was thrown, an AspectJ core file will be produced. You will find it the working directory of the compiler and it will have a name that contains the date and time that the file was produced e.g. ajcore.20060810.173655.626.txt. The file contains details of the problem such as the exception thrown as well as information about the environment such as operating system and Java version. When submitting a bug, include this file whenever it is available. By default AspectJ will only create an ajcore file when an unexpected exception is thrown by the weaver or an abort message is issued. However it is possible to disable this feature or enable files to be produced under different circumstances. The table below lists the System properties that can be used to configure ajcore files. Property Default Description org.aspectj.weaver.Dump.exception true Generate an ajcore files when an exception thrown. org.aspectj.weaver.Dump.condition abort Message kind for which to generate ajcore e.g. error. org.aspectj.dump.directory none The directory used for ajcore files. Below is an extract from an ajcore file. You will see details of the dump configuration as well as the exception (with stack trace) that is the source of the problem and any messages issued by the compiler. Most importantly the exact version of AspectJ is included. (CommonsTraceFactory.java:17) at java.lang.Class.newInstance0(Native Method) at java.lang.Class.newInstance(Class.java:232) at org.aspectj.weaver.tools.TraceFactory.(TraceFactory.java:35) at org.aspectj.weaver.World.(World.java:114) at org.aspectj.ajdt.internal.core.builder.AjBuildManager.initBcelWorld(AjBuildManager.java:679) at org.aspectj.ajdt.internal.core.builder.AjBuildManager.doBuild(AjBuildManager.java:224) at org.aspectj.ajdt.internal.core.builder.AjBuildManager.batchBuild(AjBuildManager.java:164) at org.aspectj.ajdt.ajc.AjdtCommand.doCommand(AjdtCommand.java:112) at org.aspectj.ajdt.ajc.AjdtCommand.runCommand(AjdtCommand.java:60) at org.aspectj.tools.ajc.Main.run(Main.java:367) at org.aspectj.tools.ajc.Main.runMain(Main.java:246) at org.aspectj.tools.ajc.Main.main(Main.java:86) ---- System Properties --- java.runtime.name=Java(TM) 2 Runtime Environment, Standard Edition sun.boot.library.path=C:\jdk1.3.1_16\jre\bin java.vm.version=1.3.1_16-b06 java.vm.vendor=Sun Microsystems Inc. java.vendor.url=http://java.sun.com/ path.separator=; java.vm.name=Java HotSpot(TM) Client VM file.encoding.pkg=sun.io java.vm.specification.name=Java Virtual Machine Specification user.dir=C:\workspaces\org.aspectj\org.aspectj.ant.tests java.runtime.version=1.3.1_16-b06 java.awt.graphicsenv=sun.awt.Win32GraphicsEnvironment os.arch=x86 java.io.tmpdir=C:\DOCUME~1\IBM_user\LOCALS~1\Temp\ line.separator= java.vm.specification.vendor=Sun Microsystems Inc. java.awt.fonts= os.name=Windows XP java.library.path=C:\jdk1.3.1_16\jre\bin;... java.specification.name=Java Platform API Specification java.class.version=47.0 os.version=5.1 user.home=C:\Documents and Settings\IBM_user user.timezone=Europe/London java.awt.printerjob=sun.awt.windows.WPrinterJob file.encoding=Cp1252 java.specification.version=1.3 java.class.path=C:\workspaces\org.aspectj\aj-build\dist\tools\lib\aspectjtools.jar user.name=IBM_user java.vm.specification.version=1.0 java.home=C:\jdk1.3.1_16\jre user.language=en java.specification.vendor=Sun Microsystems Inc. awt.toolkit=sun.awt.windows.WToolkit java.vm.info=mixed mode java.version=1.3.1_16 java.ext.dirs=C:\jdk1.3.1_16\jre\lib\ext sun.boot.class.path=C:\jdk1.3.1_16\jre\lib\rt.jar;... java.vendor=Sun Microsystems Inc. file.separator=\ java.vendor.url.bug=http://java.sun.com/cgi-bin/bugreport.cgi sun.io.unicode.encoding=UnicodeLittle sun.cpu.endian=little user.region=GB sun.cpu.isalist=pentium i486 i386 ---- Command Line --- -d C:\workspaces\org.aspectj\org.aspectj.ant.tests\IncrementalAjcTaskTest-temp -g:none -deprecation -noExit -warn:-unusedImport -nowarn -XterminateAfterCompilation -preserveAllLocals -proceedOnError -referenceInfo -source 1.3 -target 1.1 -time -verbose -classpath C:\workspaces\org.aspectj\org.aspectj.ant.tests\..\lib\test\aspectjrt.jar -argfile C:\workspaces\org.aspectj\taskdefs\testdata\default.lst -messageHolder org.aspectj.bridge.MessageHandler ---- Full Classpath --- Empty ---- Compiler Messages --- abort ABORT -- (NoClassDefFoundError) org/apache/commons/logging/LogFactory org/apache/commons/logging/LogFactory java.lang.NoClassDefFoundError: org/apache/commons/logging/LogFactory at org.aspectj.weaver.tools.CommonsTraceFactory.(CommonsTraceFactory.java:17) at java.lang.Class.newInstance0(Native Method) at java.lang.Class.newInstance(Class.java:232) at org.aspectj.weaver.tools.TraceFactory.(TraceFactory.java:35) at org.aspectj.weaver.World.(World.java:114) at org.aspectj.ajdt.internal.core.builder.AjBuildManager.initBcelWorld(AjBuildManager.java:679) at org.aspectj.ajdt.internal.core.builder.AjBuildManager.doBuild(AjBuildManager.java:224) at org.aspectj.ajdt.internal.core.builder.AjBuildManager.batchBuild(AjBuildManager.java:164) at org.aspectj.ajdt.ajc.AjdtCommand.doCommand(AjdtCommand.java:112) at org.aspectj.ajdt.ajc.AjdtCommand.runCommand(AjdtCommand.java:60) at org.aspectj.tools.ajc.Main.run(Main.java:367) at org.aspectj.tools.ajc.Main.runMain(Main.java:246) at org.aspectj.tools.ajc.Main.main(Main.java:86) ]]>