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MustGather: Classloader problems for WebSphere Traditional



The following MustGather will assist you in setting up the traces and collecting the data required to analyze a classloader issue.

Resolving The Problem

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Collecting data for problems with the IBM® WebSphere® Application Server classloader component. Gathering this MustGather information before calling IBM support will help you understand the problem and save time analyzing the data

This MustGather is needed to analyze exceptions such as: ClassNotFoundException, NoClassDefFoundError, ClassCastException, NoSuchMethodError, LinkageError, UnsatisfiedLinkError, VerifyError, UnsupportedClassVersionError, IncompatibleClassChangeError, ClassFormatError.

Collecting data manually

NOTE: Please see the following link for instructions to set classloader tracing on Websphere Liberty: 
MustGather: Classloader problems for WebSphere Application Server Liberty

Perform the following steps to collect WebSphere Application Server specific information. Please make sure you enable the JVM args. These are necessary for getting all of the information needed from the trace

  1. Enable Java™ Virtual Machine (JVM) classloader traces through the Admin console:
    1. Select Servers, choose Application servers and select the server you want to configure.
    2. In the Server Infrastructure section, open Java and Process Management and select Process Definition.
    3. Under Additional Properties, select Java Virtual Machine.
    4. Check the Verbose class loading checkbox.
    5. Add the following string to the Generic JVM arguments field:

      -Dws.ext.debug=true  -Dws.osgi.debug
    6. Click OK.
  2. Enable and collect Application Server traces with the following trace string:*=all

    For more details, see How to set up a trace.
  3. Save the changes. Stop the server.
  4. Clear the JVM and OSGi class cache. For more details, see How to clear the WebSphere Class Caches..
  5. Backup and delete all WebSphere log files for this WebSphere process (SystemOut*.log, SystemErr*.log, native_stderr.log, native_stdout.log, startServer.log, stopServer.log and trace.log).

    The log files are located in the following directory:


    Clear all WebSphere Application Server FFDC logs. FFDC files are located in the following directory:


    Note: If you have configured to write FFDC log files into a different location, then clear them accordingly.
  6. Restart the server. Reproduce the issue. Make sure the classloader exception is generated in the WebSphere logs (SystemOut.log) and the trace file (trace.log).
  7. Run the collector tool against the problem profile.
  8. Send the collector output to IBM: Exchanging information with IBM support.


Related information
MustGather: Read first for WebSphere Application Server

Getting started with Troubleshooting for WebSphere Application Server 

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Document Information

Modified date:
14 September 2023