This error appears in an application server's SystemOut.log.

[mm/dd/yy hh:mm:ss:sss CST] 000000e1 ServletWrappe E com.ibm.ws.webcontainer.servlet.ServletWrapper service Uncaught service() exception thrown by servlet action: java.lang.VerifyError: JVMVRFY012 stack shape inconsistent

If the application server is being monitored by Introscope, disable Introscope monitoring to see if Introscope is the cause of the issue. If the problem no longer occurs with Introscope monitoring disabled, this confirms that Introscope is the cause of the issue. In this scenario, add the following to IntroscopeAgent.profile file and then restart the application server.

introscope.autoprobe.constructor.policy=Partial
introscope.autoprobe.constructor.instrumentation.affected.vendors=Oracle,SAP,IBM

If you rule out Introscope as the cause, there may be a conflict with one or more classes in the app or one or mroe classes in a JAR file being used by the app (or both).