Solr 6.0

The Solr 5.xx files can be used for Solr 6

I had to remove solr.admin.AdminHandlers from the 5.xx version, otherwise:

4330 ERROR (coreLoadExecutor-6-thread-1) [   x:core1] o.a.s.c.CoreContainer Error creating core [core1]: Erro
r loading class 'solr.admin.AdminHandlers'
org.apache.solr.common.SolrException: Error loading class 'solr.admin.AdminHandlers'
	at org.apache.solr.core.SolrCore.<init>(SolrCore.java:771)
	at org.apache.solr.core.SolrCore.<init>(SolrCore.java:642)
	at org.apache.solr.core.CoreContainer.create(CoreContainer.java:817)
	at org.apache.solr.core.CoreContainer.access$000(CoreContainer.java:88)
	at org.apache.solr.core.CoreContainer$1.call(CoreContainer.java:468)
	at org.apache.solr.core.CoreContainer$1.call(CoreContainer.java:459)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at org.apache.solr.common.util.ExecutorUtil$MDCAwareThreadPoolExecutor.lambda$execute$0(ExecutorUtil.java:2
29)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at java.lang.Thread.run(Thread.java:745)
Caused by: org.apache.solr.common.SolrException: Error loading class 'solr.admin.AdminHandlers'
	at org.apache.solr.core.SolrResourceLoader.findClass(SolrResourceLoader.java:536)
	at org.apache.solr.core.SolrResourceLoader.findClass(SolrResourceLoader.java:467)
	at org.apache.solr.core.SolrCore.createInstance(SolrCore.java:565)
	at org.apache.solr.core.PluginBag.createPlugin(PluginBag.java:121)
	at org.apache.solr.core.PluginBag.init(PluginBag.java:221)
	at org.apache.solr.core.RequestHandlers.initHandlersFromConfig(RequestHandlers.java:130)
	at org.apache.solr.core.SolrCore.<init>(SolrCore.java:727)
	... 10 more
Caused by: java.lang.ClassNotFoundException: solr.admin.AdminHandlers
	at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
	at java.net.FactoryURLClassLoader.loadClass(URLClassLoader.java:814)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
	at java.lang.Class.forName0(Native Method)
	at java.lang.Class.forName(Class.java:348)
	at org.apache.solr.core.SolrResourceLoader.findClass(SolrResourceLoader.java:520)
	... 16 more

Which request handler did you remove from solrconfig.xml ?

None.

HTH, another factor might be that your solrconfig.xml contains:

<!-- Controls what version of Lucene various components of Solr
       adhere to.  Generally, you want to use the latest version to
       get all bug fixes and improvements. It is highly recommended
       that you fully re-index after changing this setting as it can
       affect both how text is indexed and queried.
  -->
 <luceneMatchVersion>5.0</luceneMatchVersion>

Now, I have tried a solrconfig.xml from the 6.0 examples directory, but modified to match the wpsolr settings. It works better, as it does not throw the ‘AdminHandler not found’ exception, and searching works well, but the autocomplete suggestions do not appear. Chrome Inspect shows requests to wp-admin/admin-ajax.php as you type, with a response of []. Soon I can tell you more. — Rick

I suspect you’re not using the latest version of solrconfig.xml. When I test it on my Solr 6.0.1, I see no errors like yours.