How to fix SolrException: QueryElevationComponent requires the schema to have a uniqueKeyField? - exception

Question

I am setting up a solr built into tomcat. I can get the example running in tomcat no problem. I then try to change schema.xml to a very simple one and I get an error.
This is my schema.xml
<?xml version="1.0" encoding="UTF-8" ?>
<schema name="minimal" version="1.1">
<types>
<fieldType name="string" class="solr.StrField"/>
</types>
<fields>
<dynamicField name="*" type="string" indexed="true" stored="true"/>
</fields>
</schema>
This is the error I get on start up:
May 24, 2012 10:03:33 AM org.apache.solr.core.SolrCore close
INFO: [] CLOSING SolrCore org.apache.solr.core.SolrCore#666b581a
May 24, 2012 10:03:33 AM org.apache.solr.core.QuerySenderListener newSearcher
INFO: QuerySenderListener sending requests to Searcher#2a664d5f main
May 24, 2012 10:03:33 AM org.apache.solr.update.DirectUpdateHandler2 close
INFO: closing DirectUpdateHandler2{commits=0,autocommits=0,optimizes=0,rollbacks=0,expungeDeletes=0,docsPending=0,adds=0,deletesById=0,deletesByQuery=0,errors=0,cumulative_adds=0,cumulative_deletesById=0,cumulative_deletesByQuery=0,cumulative_errors=0}
May 24, 2012 10:03:33 AM org.apache.solr.update.DirectUpdateHandler2 close
INFO: closed DirectUpdateHandler2{commits=0,autocommits=0,optimizes=0,rollbacks=0,expungeDeletes=0,docsPending=0,adds=0,deletesById=0,deletesByQuery=0,errors=0,cumulative_adds=0,cumulative_deletesById=0,cumulative_deletesByQuery=0,cumulative_errors=0}
May 24, 2012 10:03:33 AM org.apache.solr.common.SolrException log
SEVERE: java.lang.NullPointerException
at org.apache.solr.handler.component.SearchHandler.handleRequestBody(SearchHandler.java:164)
at org.apache.solr.handler.RequestHandlerBase.handleRequest(RequestHandlerBase.java:129)
at org.apache.solr.core.SolrCore.execute(SolrCore.java:1376)
at org.apache.solr.core.QuerySenderListener.newSearcher(QuerySenderListener.java:59)
at org.apache.solr.core.SolrCore$3.call(SolrCore.java:1182)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
at java.util.concurrent.FutureTask.run(FutureTask.java:166)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
at java.lang.Thread.run(Thread.java:722)
May 24, 2012 10:03:33 AM org.apache.solr.core.SolrCore execute
INFO: [] webapp=null path=null params={event=firstSearcher&q=static+firstSearcher+warming+in+solrconfig.xml} status=500 QTime=12
May 24, 2012 10:03:33 AM org.apache.solr.core.QuerySenderListener newSearcher
INFO: QuerySenderListener done.
May 24, 2012 10:03:33 AM org.apache.solr.handler.component.SpellCheckComponent$SpellCheckerListener newSearcher
INFO: Loading spell index for spellchecker: default
May 24, 2012 10:03:33 AM org.apache.solr.core.SolrCore registerSearcher
INFO: [] Registered new searcher Searcher#2a664d5f main
May 24, 2012 10:03:33 AM org.apache.solr.core.SolrCore closeSearcher
INFO: [] Closing main searcher on request.
May 24, 2012 10:03:33 AM org.apache.solr.search.SolrIndexSearcher close
INFO: Closing Searcher#2a664d5f main
fieldValueCache{lookups=0,hits=0,hitratio=0.00,inserts=0,evictions=0,size=0,warmupTime=0,cumulative_lookups=0,cumulative_hits=0,cumulative_hitratio=0.00,cumulative_inserts=0,cumulative_evictions=0}
filterCache{lookups=0,hits=0,hitratio=0.00,inserts=0,evictions=0,size=0,warmupTime=0,cumulative_lookups=0,cumulative_hits=0,cumulative_hitratio=0.00,cumulative_inserts=0,cumulative_evictions=0}
queryResultCache{lookups=0,hits=0,hitratio=0.00,inserts=0,evictions=0,size=0,warmupTime=0,cumulative_lookups=0,cumulative_hits=0,cumulative_hitratio=0.00,cumulative_inserts=0,cumulative_evictions=0}
documentCache{lookups=0,hits=0,hitratio=0.00,inserts=0,evictions=0,size=0,warmupTime=0,cumulative_lookups=0,cumulative_hits=0,cumulative_hitratio=0.00,cumulative_inserts=0,cumulative_evictions=0}
May 24, 2012 10:03:33 AM org.apache.solr.common.SolrException log
SEVERE: org.apache.solr.common.SolrException
at org.apache.solr.core.SolrCore.<init>(SolrCore.java:600)
at org.apache.solr.core.CoreContainer.create(CoreContainer.java:483)
at org.apache.solr.core.CoreContainer.load(CoreContainer.java:335)
at org.apache.solr.core.CoreContainer.load(CoreContainer.java:219)
at org.apache.solr.core.CoreContainer$Initializer.initialize(CoreContainer.java:161)
at org.apache.solr.servlet.SolrDispatchFilter.init(SolrDispatchFilter.java:96)
at org.apache.catalina.core.ApplicationFilterConfig.initFilter(ApplicationFilterConfig.java:277)
at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:258)
at org.apache.catalina.core.ApplicationFilterConfig.setFilterDef(ApplicationFilterConfig.java:382)
at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:103)
at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:4638)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5294)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:895)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:871)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:615)
at org.apache.catalina.startup.HostConfig.deployDescriptor(HostConfig.java:649)
at org.apache.catalina.startup.HostConfig$DeployDescriptor.run(HostConfig.java:1585)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
at java.util.concurrent.FutureTask.run(FutureTask.java:166)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
at java.lang.Thread.run(Thread.java:722)
Caused by: org.apache.solr.common.SolrException: QueryElevationComponent requires the schema to have a uniqueKeyField.
at org.apache.solr.handler.component.QueryElevationComponent.inform(QueryElevationComponent.java:160)
at org.apache.solr.core.SolrResourceLoader.inform(SolrResourceLoader.java:527)
at org.apache.solr.core.SolrCore.<init>(SolrCore.java:594)
... 23 more
May 24, 2012 10:03:33 AM org.apache.solr.servlet.SolrDispatchFilter init
SEVERE: Could not start Solr. Check solr/home property and the logs
org.apache.solr.common.SolrException: No cores were created, please check the logs for errors
at org.apache.solr.core.CoreContainer$Initializer.initialize(CoreContainer.java:172)
at org.apache.solr.servlet.SolrDispatchFilter.init(SolrDispatchFilter.java:96)
at org.apache.catalina.core.ApplicationFilterConfig.initFilter(ApplicationFilterConfig.java:277)
at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:258)
at org.apache.catalina.core.ApplicationFilterConfig.setFilterDef(ApplicationFilterConfig.java:382)
at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:103)
at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:4638)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5294)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:895)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:871)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:615)
at org.apache.catalina.startup.HostConfig.deployDescriptor(HostConfig.java:649)
at org.apache.catalina.startup.HostConfig$DeployDescriptor.run(HostConfig.java:1585)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
at java.util.concurrent.FutureTask.run(FutureTask.java:166)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
at java.lang.Thread.run(Thread.java:722)
May 24, 2012 10:03:33 AM org.apache.solr.common.SolrException log
SEVERE: org.apache.solr.common.SolrException: No cores were created, please check the logs for errors
at org.apache.solr.core.CoreContainer$Initializer.initialize(CoreContainer.java:172)
at org.apache.solr.servlet.SolrDispatchFilter.init(SolrDispatchFilter.java:96)
at org.apache.catalina.core.ApplicationFilterConfig.initFilter(ApplicationFilterConfig.java:277)
at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:258)
at org.apache.catalina.core.ApplicationFilterConfig.setFilterDef(ApplicationFilterConfig.java:382)
at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:103)
at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:4638)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5294)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:895)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:871)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:615)
at org.apache.catalina.startup.HostConfig.deployDescriptor(HostConfig.java:649)
at org.apache.catalina.startup.HostConfig$DeployDescriptor.run(HostConfig.java:1585)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
at java.util.concurrent.FutureTask.run(FutureTask.java:166)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
at java.lang.Thread.run(Thread.java:722)
Your help is much appreciated.

Answer 1

I think the answer is in the stack trace you provided:
Caused by: org.apache.solr.common.SolrException: QueryElevationComponent requires the schema to have a uniqueKeyField.
The example schema you've supplied doesn't have a UniqueKeyField defined
for example:
<uniqueKey>[Put name of field here]</uniqueKey>
However, as your schema doesn't define any fixed fields, you'll have to add one first.