Server Error in '/' Application.

ExecuteReader requires an open and available Connection. The connection's current state is connecting.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: System.InvalidOperationException: ExecuteReader requires an open and available Connection. The connection's current state is connecting.
Source Error:
The source code that generated this unhandled exception can only be shown when compiled in debug mode. To enable this, please follow one of the below steps, then request the URL:
1. Add a "Debug=true" directive at the top of the file that generated the error. Example:

<%@ Page Language="C#" Debug="true" %>
or:
2) Add the following section to the configuration file of your application:
<configuration>
<system.web>
<compilation debug="true"/>
</system.web>
</configuration>

Note that this second technique will cause all files within a given application to be compiled in debug mode. The first technique will cause only that particular file to be compiled in debug mode.
Important: Running applications in debug mode does incur a memory/performance overhead. You should make sure that an application has debugging disabled before deploying into production scenario.
Stack Trace:
[InvalidOperationException: ExecuteReader requires an open and available Connection. The connection's current state is connecting.]
System.Data.SqlClient.SqlConnection.GetOpenConnection(String method) +6317491
System.Data.SqlClient.SqlConnection.ValidateConnectionForExecute(String method, SqlCommand command) +13
System.Data.SqlClient.SqlCommand.ValidateCommand(String method, Boolean async) +271
System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, DbAsyncResult result) +138
System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method) +28
System.Data.SqlClient.SqlCommand.ExecuteReader(CommandBehavior behavior, String method) +256
System.Data.SqlClient.SqlCommand.ExecuteDbDataReader(CommandBehavior behavior) +19
System.Data.Common.DbCommand.System.Data.IDbCommand.ExecuteReader(CommandBehavior behavior) +21
System.Data.Common.DbDataAdapter.FillInternal(DataSet dataset, DataTable[] datatables, Int32 startRecord, Int32 maxRecords, String srcTable, IDbCommand command, CommandBehavior behavior) +325
System.Data.Common.DbDataAdapter.Fill(DataSet dataSet, Int32 startRecord, Int32 maxRecords, String srcTable, IDbCommand command, CommandBehavior behavior) +420
System.Data.Common.DbDataAdapter.Fill(DataSet dataSet) +306
AngDing.NewClass01.Dbclass.DBbase.ExecReturnDataTable(String spName, SqlParameter[] parameters) +238
AngDing.NewClass