Issue with Sitecore Solr indexes Sitecore 8.1 Update 3

Question

I am trying to convert the base Sitecore indexes from Lucene to Solr. I am using Sitecore 8.1 Update 3. I have 2 custom indexes that are still going to use Lucene for the time being so I still need the Lucene Default Index configuration enabled. Sitecore support confirmed this is allowed.

I have configured Solr, generated the schemas for these indexes, have all the cores setup in the admin for Solr. I am able to Rebuild all of the indexes using the Index Manager. My issue is that when I try to go in the content editor for example I get the following exception:

Exception: System.Xml.XmlException
Message: Data at the root level is invalid. Line 1, position 1.
Source: System.Xml
   at System.Xml.XmlTextReaderImpl.Throw(Exception e)
   at System.Xml.XmlTextReaderImpl.ParseRootLevelWhitespace()
   at System.Xml.XmlTextReaderImpl.ParseDocumentContent()
   at System.Xml.Linq.XDocument.Load(XmlReader reader, LoadOptions options)
   at System.Xml.Linq.XDocument.Parse(String text, LoadOptions options)
   at SolrNet.Impl.SolrQueryExecuter`1.Execute(ISolrQuery q, QueryOptions options)
   at Sitecore.ContentSearch.SolrProvider.LinqToSolrIndex`1.Execute(SolrCompositeQuery compositeQuery, Type resultType)
   at Sitecore.ContentSearch.SolrProvider.LinqToSolrIndex`1.FindElements[TElement](SolrCompositeQuery compositeQuery)
   at Sitecore.ContentSearch.Linq.Parsing.GenericQueryable`2.GetEnumerator()
   at System.Linq.Buffer`1..ctor(IEnumerable`1 source)
   at System.Linq.Enumerable.ToArray[TSource](IEnumerable`1 source)
   at Sitecore.ContentTesting.ContentSearch.TestingSearch.GetAllTests()
   at Sitecore.ContentTesting.Pipelines.GetContentEditorWarnings.GetContentTestingWarnings.AddSuspendedTestWarning(GetContentEditorWarningsArgs args)
   at Sitecore.ContentTesting.Pipelines.GetContentEditorWarnings.GetContentTestingWarnings.Process(GetContentEditorWarningsArgs args)
   at (Object , Object[] )
   at Sitecore.Pipelines.CorePipeline.Run(PipelineArgs args)
   at Sitecore.Shell.Applications.ContentManager.Editor.GetWarnings(Boolean hasSections)
   at Sitecore.Shell.Applications.ContentManager.Editor.Render(RenderContentEditorArgs args, Control parent)
   at Sitecore.Shell.Applications.ContentManager.ContentEditorForm.RenderEditor(Item item, Item root, Control parent, Boolean showEditor)
   at Sitecore.Shell.Applications.ContentManager.ContentEditorForm.UpdateEditor(Item folder, Item root, Boolean showEditor)
   at Sitecore.Shell.Applications.ContentManager.ContentEditorForm.Update()
   at Sitecore.Shell.Applications.ContentManager.ContentEditorForm.OnPreRendered(EventArgs e)

I am trying to pull this apart in the code, but am not having much luck at the moment. It seems strange that I can rebuild the index, but they various pieces in the Shell can't seem to use it.

Answer 1

I found the issue for my Solr problems. In my case the issue was in the Solrconfig, not Sitecore. The issue is that the default settings for the /select request somehow were changed to return JSON.

Our team has a templated set of Solr settings. Somehow those settings got edited incorrectly thus cause JSON to be returned when XML was the expected default.

Here's the configuration that caused the problem:

<requestHandler name="/select" class="solr.SearchHandler">
  <!-- default values for query parameters can be specified, these
     will be overridden by parameters in the request
  -->
   <bool name="terms">true</bool> REMOVED
   <lst name="defaults">
     <str name="echoParams">explicit</str>
     <str name="wt">json</str> REMOVED
     <str name="indent">true</str> REMOVED
     <str name="df">text</str>
     <int name="rows">10</int>
     <bool name="terms">true</bool> REMOVED
   </lst>
   <arr name="last-components">  REMOVED ELEMENT
     <str>terms</str>
   </arr>
</requestHandler>

Where the final configuration should have looked like this:

<requestHandler name="/select" class="solr.SearchHandler">
  <!-- default values for query parameters can be specified, these
  will be overridden by parameters in the request
  -->
  <lst name="defaults">
    <str name="echoParams">explicit</str>
    <int name="rows">10</int>
  </lst>
</requestHandler>

Thank you to Sitecore support for suggesting some good troubleshooting steps. We used Fiddler to figure out that our requests were returning JSON.