Rebuild Index stopped unexpectedly

Rebuild Index Error:

Job started: Index_Update_IndexName=sitecore_fxm_web_index
#Exception: System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.Data.SqlClient.SqlException: A connection was successfully established with the server, but then an error occurred during the pre-login handshake. (provider: SSL Provider, error: 0 - The wait operation timed out.) ---> System.ComponentModel.Win32Exception: The wait operation timed out
   --- End of inner exception stack trace ---
   at System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, SqlCredential credential, Object providerInfo, String newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance, SqlConnectionString userConnectionOptions, SessionData reconnectSessionData, DbConnectionPool pool, String accessToken, Boolean applyTransientFaultHandling, SqlAuthenticationProviderManager sqlAuthProviderManager)
   at System.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, DbConnectionPoolKey poolKey, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection, DbConnectionOptions userOptions)
   at System.Data.ProviderBase.DbConnectionFactory.CreatePooledConnection(DbConnectionPool pool, DbConnection owningObject, DbConnectionOptions options, DbConnectionPoolKey poolKey, DbConnectionOptions userOptions)
   at System.Data.ProviderBase.DbConnectionPool.CreateObject(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection)
   at System.Data.ProviderBase.DbConnectionPool.UserCreateRequest(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection)
   at System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, UInt32 waitForMultipleObjectsTimeout, Boolean allowCreate, Boolean onlyOneCheckConnection, DbConnectionOptions userOptions, DbConnectionInternal& connection)
   at System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal& connection)
   at System.Data.ProviderBase.DbConnectionFactory.TryGetConnection(DbConnection owningConnection, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal oldConnection, DbConnectionInternal& connection)
   at System.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
   at System.Data.SqlClient.SqlConnection.TryOpenInner(TaskCompletionSource`1 retry)
   at System.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry)
   at System.Data.SqlClient.SqlConnection.Open()
   at Sitecore.Data.DataProviders.Sql.DataProviderCommand..ctor(IDbCommand command, DataProviderTransaction transaction, Boolean openConnection)
   at Sitecore.Data.DataProviders.Sql.SqlDataApi.<>c__DisplayClass26_0.<CreateCommand>b__0()
   at Sitecore.Data.DataProviders.NullRetryer.Execute[T](Func`1 action, Action recover)
   at Sitecore.Data.DataProviders.Sql.SqlDataApi.<>c__DisplayClass29_0.<CreateReader>b__0()
   at Sitecore.Data.DataProviders.NullRetryer.Execute[T](Func`1 action, Action recover)
   at Sitecore.Data.DataProviders.Sql.SqlDataApi.CreateReader(String sql, Object[] parameters)
   at Sitecore.Data.DataProviders.Sql.SqlDataProvider.GetChildIdsByName(String childName, ID parentId)
   at Sitecore.Data.DataProviders.Sql.SqlDataProvider.ResolvePathRec(String[] path, PathCache cache, CallContext context)
   at Sitecore.Data.DataProviders.DataProvider.ResolvePath(String itemPath, CallContext context, DataProviderCollection providers)
   at Sitecore.Nexus.Data.DataCommands.ResolvePathCommand.‌‫‬‬‮‌‏‍‫‪‪‪‫‪‭‍‬‪‭‭‫​‬‮(String , Database )
   at Sitecore.Data.Engines.EngineCommand`2.Execute()
   at Sitecore.Data.Managers.ItemProvider.GetItem(String itemPath, Language language, Version version, Database database, SecurityCheck securityCheck)
   at Sitecore.ContentTesting.Pipelines.ItemProvider.GetItem.GetItemUnderTestProcessor.Process(GetItemArgs args)
   at (Object , Object )
   at Sitecore.Pipelines.CorePipeline.Run(PipelineArgs args)
   at Sitecore.Data.Managers.DefaultItemManager.GetItem(String itemPath, Language language, Version version, Database database, SecurityCheck securityCheck)
   at Sitecore.Data.Managers.DefaultItemManager.GetItem(String itemPath, Language language, Version version, Database database)
   at Sitecore.Data.Managers.ItemManager.GetItem(String itemPath, Language language, Version version, Database database)
   at Sitecore.ContentSearch.SitecoreItemCrawler.GetRootItem()
   at Sitecore.ContentSearch.SitecoreItemCrawler.get_RootItem()
   at Sitecore.ContentSearch.SitecoreItemCrawler.GetIndexableRoot()
   at Sitecore.ContentSearch.HierarchicalDataCrawler`1.RebuildFromRoot(IProviderUpdateContext context, IndexingOptions indexingOptions, CancellationToken cancellationToken)
   at Sitecore.ContentSearch.SolrProvider.SolrSearchIndex.PerformRebuild(Boolean resetIndex, Boolean optimizeOnComplete, IndexingOptions indexingOptions, CancellationToken cancellationToken)
   at Sitecore.ContentSearch.SolrProvider.SolrSearchIndex.Rebuild(Boolean resetIndex, Boolean optimizeOnComplete)
   --- End of inner exception stack trace ---
   at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor)
   at System.Reflection.RuntimeMethodInfo.UnsafeInvokeInternal(Object obj, Object[] parameters, Object[] arguments)
   at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
   at Sitecore.Reflection.ReflectionUtil.InvokeMethod(MethodInfo method, Object[] parameters, Object obj)
   at Sitecore.Jobs.JobRunner.RunMethod(JobArgs args)
   at (Object , Object )
   at Sitecore.Pipelines.CorePipeline.Run(PipelineArgs args)
   at Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args, String pipelineDomain, Boolean failIfNotExists)
   at Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args, String pipelineDomain)
   at Sitecore.Jobs.DefaultJob.DoExecute()
   at Sitecore.Abstractions.BaseJob.ThreadEntry(Object state)

Solution:
Reset IIS