ClassCastException on cargo running solr with a dataimport-handler

Question

I'm having issues on getting Solr 4.3.1 to run using the cargo-maven2-plugin. After fixing all classpath issues, I've ended up with the following error:

ERROR org.apache.solr.core.CoreContainer - null:org.apache.solr.common.SolrException: Unable to create core: collection1
    at org.apache.solr.core.CoreContainer.recordAndThrow(CoreContainer.java:1450)
    at org.apache.solr.core.CoreContainer.create(CoreContainer.java:993)
    at org.apache.solr.core.CoreContainer$2.call(CoreContainer.java:597)
    <...>
Caused by: org.apache.solr.common.SolrException: RequestHandler init failure
    at org.apache.solr.core.SolrCore.<init>(SolrCore.java:821)
    at org.apache.solr.core.SolrCore.<init>(SolrCore.java:618)
    at org.apache.solr.core.CoreContainer.createFromLocal(CoreContainer.java:949)
    at org.apache.solr.core.CoreContainer.create(CoreContainer.java:984)
    ... 10 more
Caused by: org.apache.solr.common.SolrException: RequestHandler init failure
    at org.apache.solr.core.RequestHandlers.initHandlersFromConfig(RequestHandlers.java:168)
    at org.apache.solr.core.SolrCore.<init>(SolrCore.java:758)
    ... 13 more
Caused by: org.apache.solr.common.SolrException: Error Instantiating Request Handler, org.apache.solr.handler.dataimport.DataImportHandler failed to instantiate org.apache.solr.request.SolrRequestHandler
    at org.apache.solr.core.SolrCore.createInstance(SolrCore.java:539)
    at org.apache.solr.core.SolrCore.createRequestHandler(SolrCore.java:592)
    at org.apache.solr.core.RequestHandlers.initHandlersFromConfig(RequestHandlers.java:154)
    ... 14 more
Caused by: java.lang.ClassCastException: class org.apache.solr.handler.dataimport.DataImportHandler
    at java.lang.Class.asSubclass(Class.java:3037)
    at org.apache.solr.core.SolrResourceLoader.findClass(SolrResourceLoader.java:448)
    at org.apache.solr.core.SolrResourceLoader.findClass(SolrResourceLoader.java:396)
    at org.apache.solr.core.SolrCore.createInstance(SolrCore.java:518)
    ... 16 more

I've tried with the tomcat7x and jetty7x containers. If this is a classloader problem, can I somehow force the container to use the same classloader as maven is using?

Answer 1

Going through the stack trace I did a Google search on

Error Instantiating Request Handler, \
org.apache.solr.handler.dataimport.DataImportHandler \
failed to instantiate org.apache.solr.request.SolrRequestHandl

And that brought up the following SO question.

Why can't I instantiate DataImportHandler in Solr on JBoss?

There are many answers that should help resolve the issue.