As a security feature, the JVM verifies all bytecodes in order to avoid injection of malicious code via bytecode modification. The error can also occur when:

-code is compiled against a different library than the one being used at runtime
-a class tries to extend a class declared as final
-a method tries to override a super method that is declared as final
-a wrong argument is passed to a method

The bytecode verifiier is on by default. To enable maximum verification, add the following Java command line option:

-Xverify:all

To disable the verifier, add the following Java command line option:

-Xverify:none

To enable remote strict class-loading checks on remotely loaded class use, add the following Java command line option:

-Xverify:remote

Note: For security reasons, never disable bytecode verification on a production system

It most cases, verify errors are the result incompatible 3rd party libraries. The diagnostic message will identify any inconsistent class and method. For example:

java.lang.VerifyError: JVMVRFY012 stack shape inconsistent;
class=com/sun/xml/messaging/saaj/soap/SOAPDocumentImpl,
method=createDocumentFragment()Lorg/w3c/dom/DocumentFragment;, pc=5

To locate the jar file a class is being loaded from, add -verbose:dynload and -verbose:class to your Java command line

Make sure you compile all classes with the same Java version. Please reference only the public class of the Java API. Your code should not depend on internal classes which are subject to change.

If, after reading and following the above instructions, further assistance is required, please complete the following steps:

1. Confirm that you have review and completed all of the above steps.

2. Contact IBM and open a new IBM service request (i.e., a new IBM PMR).

3. Collect and upload data as per the data collection procedures noted in the above sections or package and upload the current data and details by following the instructions on this web page:

IBM Java for AIX MustGather: How to upload diagnostic data and testcases to IBM