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Cannot install burp extensions in 2021.5.1 of Burp Pro

Rahim | Last updated: May 15, 2021 08:00PM UTC

I get the following error when I manually install *any* extension: java.lang.ClassNotFoundException: burp.BurpExtender at java.base/java.net.URLClassLoader.findClass(URLClassLoader.java:435) at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:589) at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:522) at java.base/java.lang.Class.forName0(Native Method) at java.base/java.lang.Class.forName(Class.java:468) at burp.d3n.a(Unknown Source) at burp.d3n.<init>(Unknown Source) at burp.dxk.a(Unknown Source) at burp.hrt.lambda$panelLoaded$0(Unknown Source) at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515) at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264) at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130) at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:630) at java.base/java.lang.Thread.run(Thread.java:832)

Rahim | Last updated: May 15, 2021 08:07PM UTC

And yes, I've got jython installed and configured in burp (under python runtime)

Rahim | Last updated: May 15, 2021 08:13PM UTC

Nvm fixed now. Interesting it installed successfully when I tried installing via Extender -> BApp Store -> Manual Install -> point to .bapp file. However, still failing to install via Extender -> Extensions -> Add -> point to .bapp file

Uthman, PortSwigger Agent | Last updated: May 17, 2021 08:30AM UTC

Hi Rahim, Glad to hear that your issue is resolved. What you are seeing is expected behavior. If you are installing a Bapp via Extender -> Extensions -> Add, you need to point Burp to the JAR or .py file. For a manual install, we expect a .bapp file.

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