I was trying to use Wsdler plug-in into Burp. As per Eric's article, this plug-in should work fine with Burp version>= 1.5.01 and it worked fine with the Pro edition but when I try to use this plug-in with the free edition, I am getting following error Exception thrown by BurpExtender.registerExtenderCallbacks(): java.lang.AbstractMethodError: burp.x4.getHelpers()Lburp/IExtensionHelpers; What is the version of Burp free edition? Is it <1.5.01? URL for Wsdler Plug-in > https://www.netspi.com/blog/entryid/57/hacking-web-services-with-burp -- Thanks, Pankaj Upadhyay