Resolution:
Title:
I got the following error on the file poller after installing iProcess Insight (Latest version):

java.lang.NoSuchMethodError: com.tibco.pe.plugin.ConfigErrorsHelper.addResourceBundle(Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;)V
    at com.tibco.plugin.file.FileEventSource.getConfigErrors(FileEventSource.java:162)
    at com.tibco.pe.model.ProcessReport.int(ProcessReport.java:894)
    at com.tibco.pe.model.ProcessReport.&ltinit>(ProcessReport.java:194)
    at com.tibco.ae.tools.palettes.processpalette.ProcessDefinitionValidationSupport.validateForDeployment(ProcessDefinitionValidationSupport.java:61)
    at com.tibco.ae.tools.palettes.processpalette.ProcessDefinition.validateForDeployment(ProcessDefinition.java:3927)
    at com.tibco.ae.designerapi.DesignerGroupResource.validateForDeployment(DesignerGroupResource.java:363)
    at com.tibco.ae.designerapi.DesignerGroupResource.validateForDeployment(DesignerGroupResource.java:363)
    at com.tibco.ae.designerapi.RootFolder.validateForDeployment(RootFolder.java:620)
    at com.tibco.ae.designerapi.AEResourceUtils.validateForDeployment(AEResourceUtils.java:1972)
    at com.tibco.ae.tools.designer.actions.ValidateProjectAction.runValidation(ValidateProjectAction.java:160)
    at com.tibco.ae.tools.designer.actions.ValidateProjectAction.runValidation(ValidateProjectAction.java:93)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:585)
    at com.tibco.util.Trampoline.invoke(Trampoline.java:166)
    at com.tibco.ui.BusyWait.run(BusyWait.java:424)
    at java.lang.Thread.run(Thread.java:595)

What can be the issue here?

Resolution:
This is a known issue in BW where mapper.jar is loaded before engine.jar...
But for BW the workaround is to have engine.jar ahead of mapper.jar in the classpath of designer.tra if you start BW engine from Designer, or in the deployed TRA file if you run the project from Administrator.

Ex:  
tibco.env.CUSTOM_EXT_PREPEND_CP=%BW_HOME%/hotfix/lib/engine.jar%PSP%%BW_HOME%/lib/engine.jar