An instance of one of our Nintex Workflows 2010 failed and I tried to investigate the reason of it. Based on the graphical view, the error was on the web service call action, but when I tried to look what has been logged (procedure that we do when something errors), I realized that once I click on "Click here to show detailed view", after some time, I am getting an "unexpected" error at the user interface which on the logs correspont to the below:
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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.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()
at Nintex.Workflow.Reports.ActivityLogInfoCollection..ctor(Int64 internalInstanceId, SPWeb web, Boolean includeVerboseLogging)
at Nintex.Workflow.Reports.WorkflowLog..ctor(Guid workflowInstanceId, SPWeb web, Boolean includeVerboseLogging)
at Nintex.Workflow.Reports.WorkflowLog..ctor(Guid workflowInstanceId, SPWeb web)
at Nintex.Workflow.ApplicationPages.WorkflowLog.Page_Load(Object sender, EventArgs e)
at System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e)
at System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e)
at System.Web.UI.Control.OnLoad(EventArgs e)
at Microsoft.SharePoint.WebControls.UnsecuredLayoutsPageBase.OnLoad(EventArgs e)
at Microsoft.SharePoint.WebControls.LayoutsPageBase.OnLoad(EventArgs e)
at Nintex.Workflow.ServerControls.NintexLayoutsBase.OnLoad(EventArgs e)
at System.Web.UI.Control.LoadRecursive()
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
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Then I realized that the same error happens no matter which workflow instance I tried to see the details - even those that successfully completed.