Issue with Episerver Find CMS Reindexing Scheduled Job

Hi,

We are currently facing constant issues of site going down for almost on everyday for Production Site. This happenes almost at every 3 hours of time gap which is the duration set to run the Episerver.Find Reindexing job on the CMS. 

• The two page Files which are mentioned in the below log Error, they do not present on the CMS. 
• When i try to execute the indexing job manually i see no error but when it happns automatically i see below errors and continuous outages. 
• The Episerver version is Episerver CMS 7.0 and Episerver.Find.CMS  DLL version is 7.0.586.0

2017-07-03 00:10:48,287 [32] ERROR EPiServer.Global: 1.2.5 Unhandled exception in ASP.NET
System.Web.HttpUnhandledException (0x80004005): Exception of type 'System.Web.HttpUnhandledException' was thrown. ---> EPiServer.Find.ServiceException: The remote server returned an error: (400) Bad Request.
SearchPhaseExecutionException[Failed to execute phase [query], all shards failed; shardFailures {[BQ_eWjzaR3W9LrRgbRnYaQ][aquaproducts_index50292][0]: RemoteTransportException[[sefindprod02esd04][inet[/10.3.151.4:9300]][search/phase/query]]; nested: SearchParseException[[aquaproducts_index50292][0]: from[-1],size[-1]: Parse Failure [Failed to parse source [{"query":{"filtered":{"query":{"filtered":{"query":{"query_string":{"fields":["Name$$string.standard","Title$$string.standard","SubTitle$$string.standard","Teaser$$string.standard","OverrideNavigationTitle$$string.standard","BrowserTitle$$string.standard","MetaKeywords$$string.standard","MainContent.AsViewedByAnonymous$$string.standard"],"query":"\\[url=https\\:\\/\\/center.renthop.net\\/townhouses\\/4939\\-houses\\-to\\-rent\\-in\\-county\\-down\\-northern\\-ireland.html\\]houses to rent in county down northern ireland\\[/url\\]"}},"filter":{"term":{"LanguageBranch$$string":"en"}}}},"filter":{"term":{"___types":"aquabots.com.Page_Types.Aquabots.Generic.GenericPage"}}}},"fields":["___types","PageLink.ID$$number","PageLink.ProviderName$$string"]}]]]; nested: QueryParsingException[[aquaproducts_index50292] Failed to parse query [\[url=https\:\/\/center.renthop.net\/townhouses\/4939\-houses\-to\-rent\-in\-county\-down\-northern\-ireland.html\]houses to rent in county down northern ireland\[/url\]]]; nested: ParseException[Cannot parse '\[url=https\:\/\/center.renthop.net\/townhouses\/4939\-houses\-to\-rent\-in\-county\-down\-northern\-ireland.html\]houses to rent in county down northern ireland\[/url\]': Lexical error at line 1, column 170.  Encountered: <EOF> after : "/url\\]"]; nested: TokenMgrError[Lexical error at line 1, column 170.  Encountered: <EOF> after : "/url\\]"]; }{[vwhC_QFVRSCt3Iu4HihV1A][aquaproducts_index50292][1]: SearchParseException[[aquaproducts_index50292][1]: from[-1],size[-1]: Parse Failure [Failed to parse source [{"query":{"filtered":{"query":{"filtered":{"query":{"query_string":{"fields":["Name$$string.standard","Title$$string.standard","SubTitle$$string.standard","Teaser$$string.standard","OverrideNavigationTitle$$string.standard","BrowserTitle$$string.standard","MetaKeywords$$string.standard","MainContent.AsViewedByAnonymous$$string.standard"],"query":"\\[url=https\\:\\/\\/center.renthop.net\\/townhouses\\/4939\\-houses\\-to\\-rent\\-in\\-county\\-down\\-northern\\-ireland.html\\]houses to rent in county down northern ireland\\[/url\\]"}},"filter":{"term":{"LanguageBranch$$string":"en"}}}},"filter":{"term":{"___types":"aquabots.com.Page_Types.Aquabots.Generic.GenericPage"}}}},"fields":["___types","PageLink.ID$$number","PageLink.ProviderName$$string"]}]]]; nested: QueryParsingException[[aquaproducts_index50292] Failed to parse query [\[url=https\:\/\/center.renthop.net\/townhouses\/4939\-houses\-to\-rent\-in\-county\-down\-northern\-ireland.html\]houses to rent in county down northern ireland\[/url\]]]; nested: ParseException[Cannot parse '\[url=https\:\/\/center.renthop.net\/townhouses\/4939\-houses\-to\-rent\-in\-county\-down\-northern\-ireland.html\]houses to rent in county down northern ireland\[/url\]': Lexical error at line 1, column 170.  Encountered: <EOF> after : "/url\\]"]; nested: TokenMgrError[Lexical error at line 1, column 170.  Encountered: <EOF> after : "/url\\]"]; }] ---> System.Net.WebException: The remote server returned an error: (400) Bad Request.
   at System.Net.HttpWebRequest.GetResponse()
   at EPiServer.Find.Connection.JsonRequest.GetResponse()
   at EPiServer.Find.Api.Command.GetResponse[TResult](IJsonRequest request)
   --- End of inner exception stack trace ---
   at EPiServer.Find.Api.Command.GetResponse[TResult](IJsonRequest request)
   at EPiServer.Find.Api.SearchCommand`1.Execute()
   at EPiServer.Find.Client.Search[TSource](SearchRequestBody requestBody, Action`1 commandAction)
   at EPiServer.Find.SearchExtensions.GetProjectedResult[TResult](ISearch`1 search, SearchContext context)
   at EPiServer.Find.SearchExtensions.GetResult[TResult](ISearch`1 search)
   at EPiServer.Find.Cms.SearchRequestExtensions.GetPagesResult[TPageData](ITypeSearch`1 search, LanguageSelector languageSelector)
   at aquabots.com.Templates.Aquabots.Units.Global.SiteSearchListing.BindDetails()
   at aquabots.com.Templates.Aquabots.Units.Global.SiteSearchListing.Page_Load(Object sender, EventArgs e)
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
   at System.Web.UI.Page.HandleError(Exception e)
   at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
   at System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
   at System.Web.UI.Page.ProcessRequest()
   at System.Web.UI.Page.ProcessRequest(HttpContext context)
   at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
   at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)
2017-07-03 00:35:41,357 [75] ERROR EPiServer.Find.Cms.ContentIndexer: An exception occured while indexing (Batch): You are not authorized to access /PageFiles/2463/. 
System.UnauthorizedAccessException: You are not authorized to access /PageFiles/2463/
   at EPiServer.Web.Hosting.VirtualPathVersioningProvider.GetDirectory(String virtualPath)
   at EPiServer.Web.Hosting.VirtualPathVersioningProvider.GetDirectory(String virtualPath)
   at EPiServer.Web.Hosting.VirtualPathVersioningProvider.GetDirectory(String virtualPath)
   at EPiServer.Web.Hosting.VirtualPathNonUnifiedProvider.GetDirectory(String virtualDir)
   at EPiServer.Web.Hosting.VirtualPathNonUnifiedProvider.GetDirectory(String virtualDir)
   at EPiServer.Web.Hosting.VirtualPathNonUnifiedProvider.GetDirectory(String virtualDir)
   at EPiServer.Web.Hosting.VirtualPathNonUnifiedProvider.GetDirectory(String virtualDir)
   at EPiServer.Find.Cms.ContentExtensions.GetPageFiles(PageData page)
   at EPiServer.Find.Cms.ContentIndexer.Index(IEnumerable`1 content, IndexOptions options)
   at EPiServer.Find.Cms.ContentIndexer.ReIndex(Action`1 statusAction, Func`1 isStopped)
2017-07-03 00:35:44,976 [75] ERROR EPiServer.Find.Cms.ContentIndexer: An exception occured while indexing (Batch): You are not authorized to access /PageFiles/2255/. 
System.UnauthorizedAccessException: You are not authorized to access /PageFiles/2255/
   at EPiServer.Web.Hosting.VirtualPathVersioningProvider.GetDirectory(String virtualPath)
   at EPiServer.Web.Hosting.VirtualPathVersioningProvider.GetDirectory(String virtualPath)
   at EPiServer.Web.Hosting.VirtualPathVersioningProvider.GetDirectory(String virtualPath)
   at EPiServer.Web.Hosting.VirtualPathNonUnifiedProvider.GetDirectory(String virtualDir)
   at EPiServer.Web.Hosting.VirtualPathNonUnifiedProvider.GetDirectory(String virtualDir)
   at EPiServer.Web.Hosting.VirtualPathNonUnifiedProvider.GetDirectory(String virtualDir)
   at EPiServer.Web.Hosting.VirtualPathNonUnifiedProvider.GetDirectory(String virtualDir)
   at EPiServer.Find.Cms.ContentExtensions.GetPageFiles(PageData page)
   at EPiServer.Find.Cms.ContentIndexer.Index(IEnumerable`1 content, IndexOptions options)
   at EPiServer.Find.Cms.ContentIndexer.ReIndex(Action`1 statusAction, Func`1 isStopped)
2017-07-03 00:42:56,771 [11] ERROR EPiServer.Global: 1.2.5 Unhandled exception in ASP.NET
System.Web.HttpUnhandledException (0x80004005): Exception of type 'System.Web.HttpUnhandledException' was thrown. ---> System.InvalidOperationException: Collection was modified; enumeration operation may not execute.
   at System.Collections.Generic.List`1.Enumerator.MoveNextRare()
   at BVNetwork.Bvn.FileNotFound.Logging.Logger.LogRequests(List`1 logEvents)
   at BVNetwork.Bvn.FileNotFound.Logging.Logger.LogRequest(String oldUrl, String referer)
   at BVNetwork.FileNotFound.NotFoundPageUtil.HandleOnLoad(Page page, Uri urlNotFound, String referer)
   at System.Web.UI.Control.LoadRecursive()
   at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
   at System.Web.UI.Page.HandleError(Exception e)
   at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
   at System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
   at System.Web.UI.Page.ProcessRequest()
   at System.Web.UI.Page.ProcessRequest(HttpContext context)
   at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
   at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)
2017-07-03 01:36:40,517 [34] ERROR EPiServer.Global: 1.2.5 Unhandled exception in ASP.NET

Please suggest here what is going on. 

Thanks,

Hiral shah