IBM Support

MustGather: Classloader problems for WebSphere Application Server

Technote (troubleshooting)


The following MustGather will assist you in setting up the traces and collecting the data required to analyze a classloader issue. This MustGather is needed to analyze exceptions such as:
ClassNotFoundException, NoClassDefFoundError, ClassCastException, NoSuchMethodError, LinkageError, UnsatisfiedLinkError, VerifyError, UnsupportedClassVersionError.

Resolving the problem

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.

To improve the accuracy of complete data collection, IBM recommends you use the automated data collectors within IBM Support Assistant. Not only will the automated collector gather the equivalent of the manual process, it will also provide a secure file transfer of the collection to IBM.

Collecting data using the IBM Support Assistant Data Collector

    Beginning with WebSphere Application Server V8.0.0.6, the IBM Support Assistant Data Collector (ISADC) tool is bundled with the product and is automatically installed. As a result, you can run the  ISADC tool directly from the app_server_root/bin directory. For more details, see Using the IBM Support Assistant Data Collector.

  1. Using the ISA Data Collector:
    • To run ISADC from command line, go to your app_server_root/bin directory and run isadc.[sh|bat]

      • To download, install and run ISADC locally:
      • Obtain the IBM Support Assistant Data collector online ISA Data Collector site for WebSphere Application Server.
      • Select the option to collect from this or another system using a downloadable utility.
      • Download and extract the zip file to your WAS_HOME directory. From a command line, run isadc.[sh|bat] or launch index.html to use the web interface.

  2. Select the Runtime > Classloader Problem collector and click Start.

  3. Follow the prompts to automatically submit the collected data to IBM Support.

Collecting data manually

NOTE: Please see the following link for instructions for Liberty Profile:
MustGather: Classloader problems for WebSphere Application Server Liberty Profile

Perform the following steps to collect WebSphere Application Server specific information.

  1. Enable and collect Application Server traces with the following trace string:*=all

    For more details, see How to set up a trace.

  2. 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.

  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
Submitting information to IBM support
Steps to getting support for WebSphere Application Server
MustGather: Read first for WebSphere Application Server
Troubleshooting guide for WebSphere Application Server

Exchanging data with IBM Support

To diagnose or identify a problem, it is sometimes necessary to provide Technical Support with data and information from your system. In addition, Technical Support might also need to provide you with tools or utilities to be used in problem determination. You can submit files using one of following methods to help speed problem diagnosis:

Read first and related MustGathers

Related information

Recording your screen to share with IBM Support

Cross reference information
Segment Product Component Platform Version Edition
Application Servers WebSphere Application Server - Express Java SDK AIX, HP-UX, Linux, Solaris, Windows 8.5, 8.0, 7.0, 6.1, 6.0
Application Servers Runtimes for Java Technology Java SDK

Document information

More support for: WebSphere Application Server

Software version: 6.0, 6.1, 7.0, 8.0, 8.5, 8.5.5

Operating system(s): AIX, HP-UX, Linux, Solaris, Windows

Software edition: Base, Express, Network Deployment

Reference #: 1196187

Modified date: 08 August 2013