I'm getting the following Scheduler Exception after upgrading to 4.3.5. Can anyone tell me what could be generating this error?

AssemblyVersion: -1
PortalID: -1
PortalName:
UserID: -1
UserName:
ActiveTabID: -1
ActiveTabName:
RawURL:
AbsoluteURL:
AbsoluteURLReferrer:
UserAgent:
DefaultDataProvider:
ExceptionGUID:
InnerException: Add failed. Duplicate key value supplied.
FileName:
FileLineNumber: -1
FileColumnNumber: -1
Method:
StackTrace:
Message: System.ArgumentException: Add failed. Duplicate key value supplied. at Microsoft.VisualBasic.Collection.Add(Object Item, String Key, Object Before, Object After) at DotNetNuke.Services.Scheduling.DNNScheduling.Scheduler.CoreScheduler.AddToScheduleQueue(ScheduleHistoryItem objScheduleHistoryItem) at DotNetNuke.Services.Scheduling.DNNScheduling.Scheduler.CoreScheduler.LoadQueueFromTimer() at DotNetNuke.Services.Scheduling.DNNScheduling.Scheduler.CoreScheduler.Start()

I encounter same problem. The scheduler is filling the eventlog. I have the idea since the database connection times out. I have also seen the duplicate key thing, but after 13.000 logs I had to clear up the log. At the end the website crashes.

I solve it by clearing event log and do an application restart (rename web.config to _web.config and rename it back to web.config will give a restart). Since the website is not accessible anymore you have to use enterprise manager to do this. I have a keepalive HTTP header running...but the problem only started today..after performanced degration over the last month...at one of the hosting providers advertising here as well! I have 4.3.5 version.

delete from dbo.{objectqualifier}EventLog

<ArrayOfAnyType xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"><anyType xsi:type="LogDetailInfo"><name>AssemblyVersion</name><value>-1</value></anyType><anyType xsi:type="LogDetailInfo"><name>PortalID</name><value>-1</value></anyType><anyType xsi:type="LogDetailInfo"><name>PortalName</name></anyType><anyType xsi:type="LogDetailInfo"><name>UserID</name><value>-1</value></anyType><anyType xsi:type="LogDetailInfo"><name>UserName</name></anyType><anyType xsi:type="LogDetailInfo"><name>ActiveTabID</name><value>-1</value></anyType><anyType xsi:type="LogDetailInfo"><name>ActiveTabName</name><value /></anyType><anyType xsi:type="LogDetailInfo"><name>RawURL</name><value /></anyType><anyType xsi:type="LogDetailInfo"><name>AbsoluteURL</name><value /></anyType><anyType xsi:type="LogDetailInfo"><name>AbsoluteURLReferrer</name><value /></anyType><anyType xsi:type="LogDetailInfo"><name>UserAgent</name><value /></anyType><anyType xsi:type="LogDetailInfo"><name>DefaultDataProvider</name><value /></anyType><anyType xsi:type="LogDetailInfo"><name>ExceptionGUID</name><value /></anyType><anyType xsi:type="LogDetailInfo"><name>InnerException</name><value>Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding.</value></anyType><anyType xsi:type="LogDetailInfo"><name>FileName</name><value /></anyType><anyType xsi:type="LogDetailInfo"><name>FileLineNumber</name><value>-1</value></anyType><anyType xsi:type="LogDetailInfo"><name>FileColumnNumber</name><value>-1</value></anyType><anyType xsi:type="LogDetailInfo"><name>Method</name><value /></anyType><anyType xsi:type="LogDetailInfo"><name>StackTrace</name></anyType><anyType xsi:type="LogDetailInfo"><name>Message</name><value>System.Data.SqlClient.SqlException: Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding. at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection) at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection) at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj) at System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj) at System.Data.SqlClient.SqlDataReader.ConsumeMetaData() at System.Data.SqlClient.SqlDataReader.get_MetaData() at System.Data.SqlClient.SqlCommand.FinishExecuteReader(SqlDataReader ds, RunBehavior runBehavior, String resetOptionsString) at System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async) at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, DbAsyncResult result) at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method) at System.Data.SqlClient.SqlCommand.ExecuteReader(CommandBehavior behavior, String method) at System.Data.SqlClient.SqlCommand.ExecuteReader(CommandBehavior behavior) at Microsoft.ApplicationBlocks.Data.SqlHelper.ExecuteReader(SqlConnection connection, SqlTransaction transaction, CommandType commandType, String commandText, SqlParameter[] commandParameters, SqlConnectionOwnership connectionOwnership) at Microsoft.ApplicationBlocks.Data.SqlHelper.ExecuteReader(String connectionString, CommandType commandType, String commandText, SqlParameter[] commandParameters) at Microsoft.ApplicationBlocks.Data.SqlHelper.ExecuteReader(String connectionString, String spName, Object[] parameterValues) at DotNetNuke.Services.Scheduling.DNNScheduling.SqlDataProvider.GetSchedule(String Server) at DotNetNuke.Services.Scheduling.DNNScheduling.SchedulingController.GetSchedule(String Server) at DotNetNuke.Services.Scheduling.DNNScheduling.Scheduler.CoreScheduler.LoadQueueFromTimer() at DotNetNuke.Services.Scheduling.DNNScheduling.Scheduler.CoreScheduler.Start()</value></anyType><anyType xsi:type="LogDetailInfo"><name>Source</name></anyType></ArrayOfAnyType>