Description

An exception might occur with an MVC site if the Solr server is stopped. This happens because of the Sitecore.Mvc.ExperienceEditor.DatasourceValidator.DatasourceValidator.IsDatasourceValid method that tries to use search functionality for checking the data source. The log might contain the following error:

Failed to execute datasource query System.NullReferenceException: Object reference not set to an instance of an object.
   at Sitecore.ContentSearch.SitecoreItemCrawler.IsExcludedFromIndex(SitecoreIndexableItem indexable, Boolean checkLocation)
   at Sitecore.ContentSearch.SitecoreItemCrawler.GetContextIndexRanking(IIndexable indexable)
   at System.Linq.Enumerable.WhereSelectListIterator`2.MoveNext()
   at System.Linq.Enumerable.Min(IEnumerable`1 source)
   at Sitecore.ContentSearch.AbstractSearchIndex.Sitecore.ContentSearch.Pipelines.GetContextIndex.IContextIndexRankable.GetContextIndexRanking(IIndexable indexable)
   at Sitecore.ContentSearch.Pipelines.GetContextIndex.FetchIndex.<>c__DisplayClass6_0.<RankContextIndexes>b__0(ISearchIndex i)
   at System.Linq.Enumerable.WhereSelectEnumerableIterator`2.MoveNext()
   at System.Linq.Buffer`1..ctor(IEnumerable`1 source)
   at System.Linq.OrderedEnumerable`1.<GetEnumerator>d__1.MoveNext()
   at System.Linq.Buffer`1..ctor(IEnumerable`1 source)
   at System.Linq.Enumerable.ToArray[TSource](IEnumerable`1 source)
   at Sitecore.ContentSearch.Pipelines.GetContextIndex.FetchIndex.GetContextIndex(IIndexable indexable, GetContextIndexArgs args)
   at Sitecore.ContentSearch.Pipelines.GetContextIndex.FetchIndex.Process(GetContextIndexArgs args)
   at (Object , Object[] )
   at Sitecore.Pipelines.CorePipeline.Run(PipelineArgs args)
   at Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args, String pipelineDomain)
   at Sitecore.Abstractions.CorePipelineWrapper.Run(String pipelineName, PipelineArgs args)
   at Sitecore.ContentSearch.Pipelines.GetContextIndex.GetContextIndexPipeline.Run(ICorePipeline pipeline, GetContextIndexArgs args)
   at Sitecore.Mvc.ExperienceEditor.DatasourceValidator.DatasourceValidator.IsDatasourceValid(String dataSource, Database database)

Solution

To resolve the issue, consider one of the following options:

• Upgrade Sitecore XP instance to Sitecore XP 9.0.2 or later.
• For Sitecore XP 9.0.1, download and install the patch compatible with the affected product version found on this page: https://github.com/SitecoreSupport/Sitecore.Support.212959/releases