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Problem with BurpSuite

Aleksandar | Last updated: Jul 13, 2017 12:44PM UTC

After activating BurpSuite, I've used it once to scan some web. Next time I tried to start it, I receive following error: va.lang.ClassNotFoundException: burp.StartBurp at java.net.URLClassLoader.findClass(URLClassLoader.java:381) at java.lang.ClassLoader.loadClass(ClassLoader.java:424) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331) at java.lang.ClassLoader.loadClass(ClassLoader.java:357) at com.exe4j.runtime.LauncherEngine.launch(LauncherEngine.java:62) at com.exe4j.runtime.WinLauncher.main(WinLauncher.java:101) at com.install4j.runtime.launcher.WinLauncher.main(WinLauncher.java:26)

PortSwigger Agent | Last updated: Jul 13, 2017 02:13PM UTC

Hi Aleksandar, Thanks for getting in touch. This is a most unusual problem. Can I suggest you start by completely uninstalling, then reinstalling Burp. If you're still having trouble, this could be anti-virus software incorrectly flagging Burp as malware. In that case, add an exclusion for Burp's directory, then reinstall Burp. Please let us know if you need any further assistance.

Burp User | Last updated: Aug 04, 2017 07:36AM UTC

I got the same issue when updating Burp Pro from 1.7.16 to 1.7.26 on Windows 10 x64. No errors with the AV and I have also removed and re-installed the Burp Suite again. First time I start the application it works fine. Quit and start again, the error message appears. java.lang.ClassNotFoundException: burp.StartBurp at java.net.URLClassLoader.findClass(URLClassLoader.java:381) at java.lang.ClassLoader.loadClass(ClassLoader.java:424) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331) at java.lang.ClassLoader.loadClass(ClassLoader.java:357) at com.exe4j.runtime.LauncherEngine.launch(LauncherEngine.java:62) at com.exe4j.runtime.WinLauncher.main(WinLauncher.java:101) at com.install4j.runtime.launcher.WinLauncher.main(WinLauncher.java:26)

PortSwigger Agent | Last updated: Aug 07, 2017 10:41AM UTC

Hi Mats, Even though you get no AV messages, this really sounds like an AV problem. Burp does not modify its own jar file, so if it's working once and not after that implies something else is modifying it. Please try disabling all AV software on your system, including Defender, and see if the problem continues.

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