Why am I getting a NoClassDefFoundError on HttpServletRequest that is pointing to ServletFileUpload?

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Solution 1

All 3rd party webapp libraries like Commons FileUpload belong in /WEB-INF/lib of your webapp, not elsewhere. This exception can occur whenever you've placed it in JRE/lib or JRE/lib/ext.

And indeed, as Bozho mentions, you need to ensure as well that you haven't moved/copied/duplicated any servletcontainer-specific libraries (which should be left untouched in Tomcat/lib) around in different places of the classpath. But that should IMO not have resulted in this kind of exception. It's basically telling that the classloader which loaded the FileUpload API has totally no knowledge about the Servlet API.

If you read the Tomcat classloading HOW-TO, then you'll see that the libraries in JRE/lib and JRE/lib/ext are loaded by a different classloader (bootstrap) than the ones in Tomcat/lib (common) and /WEB-INF/lib (webapp). The bootstrap classloader has no knowledge about common and webapp libraries. It's the other way round. The common classloader has knowledge about the bootstrap classloader and the webapp classloader has knowledge about both. Since the Servlet API is normally loaded by the common classloader, this can only mean that the FileUpload API was loaded by the bootstrap classloader. And this is wrong :)

Solution 2

This means that your servlet container does not have the servlet api. Take a clean installation of Tomcat and try to deploy there. First check that you have the servlet api jar in tomcat/lib. And make sure you don't have it in webapps/yourapp/WEB-INF/lib

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katura
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katura

Updated on June 09, 2022

Comments

  • katura
    katura over 1 year

    I recently started using JMeter to load test my webapp, locally on my pc. I have a jsp page for uploading images. The images are processed by my servlet. When I tried the process today, I got the following exception/error :

    exception
    
    javax.servlet.ServletException: Servlet execution threw an exception
    
    root cause
    
    java.lang.NoClassDefFoundError: javax/servlet/http/HttpServletRequest
        org.apache.commons.fileupload.servlet.ServletFileUpload.isMultipartContent(ServletFileUpload.java:68)
        spyder.servlets.imageProcessing.ImageProcessingServlet.uploadEditedImagesToDB(ImageProcessingServlet.java:527)
        spyder.servlets.imageProcessing.ImageProcessingServlet.doPost(ImageProcessingServlet.java:153)
        javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
        javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    

    Here is the code from my servlet that the exception is referring to -

    boolean isPart = ServletFileUpload.isMultipartContent(req);
    

    ....and yes, I've put all the necessary import statements in the class.

    I can't recall making any changes to anything on my system that would cause this problem. This process has always run without any problems, so I don't understand what is causing it to fail like this now. Its rather coincidental, I think, that it is failing after I've been using JMeter...

  • katura
    katura almost 13 years
    Yes, the servlet-api.jar is in c:\jakarta-tomcat\lib only. I'm running Tomcat 6.0.29.
  • Bozho
    Bozho almost 13 years
    @katura - just try it on a fresh installation. Install = unzip.
  • katura
    katura almost 13 years
    Thank you for pointing out my error. I removed the 3rd party jars from the jre/lib/ext folder (I had copied them in there), and after a restart (not reinstall) of Tomcat, the process is back up and running as it was.