Question

I’m having troubles with an asp.net 2.0 application that I took over from other developers (meaning I don’t really know much of the code). It is throwing an unhandled exception, but I cannot get any source info where exactly the exception occurs, and debug stepping through the source suddenly ends with the only option of showing disassembly code.

Is there anything else I can do in VS2005 or IIS to figure out where exactly the exception occurs?

Below is the output of the IIS error message (that usually shows source files, line numbers etc, but not in this case).

thanks.

String or binary data would be truncated. 
The statement has been terminated. 
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.Data.SqlClient.SqlException: String or binary data would be truncated. 
The statement has been terminated.

Source Error: 

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.  

Stack Trace: 


[SqlException (0x80131904): String or binary data would be truncated. The statement has been terminated.]
   System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection) +1950890
   System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection) +4846875
   System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj) +194
   System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj) +2392
   System.Data.SqlClient.SqlDataReader.SetMetaData(_SqlMetaDataSet metaData, Boolean moreInfo) +125
   System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj) +1908
   System.Data.SqlClient.SqlDataReader.ConsumeMetaData() +33
   System.Data.SqlClient.SqlDataReader.get_MetaData() +83
   System.Data.SqlClient.SqlCommand.FinishExecuteReader(SqlDataReader ds, RunBehavior runBehavior, String resetOptionsString) +297
   System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async) +954
   System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, DbAsyncResult result) +162
   System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method) +32
   System.Data.SqlClient.SqlCommand.ExecuteReader(CommandBehavior behavior, String method) +141
   System.Data.SqlClient.SqlCommand.ExecuteDbDataReader(CommandBehavior behavior) +12
   System.Data.Common.DbCommand.System.Data.IDbCommand.ExecuteReader(CommandBehavior behavior) +10
   System.Data.Common.DbDataAdapter.FillInternal(DataSet dataset, DataTable[] datatables, Int32 startRecord, Int32 maxRecords, String srcTable, IDbCommand command, CommandBehavior behavior) +130
   System.Data.Common.DbDataAdapter.Fill(DataSet dataSet, Int32 startRecord, Int32 maxRecords, String srcTable, IDbCommand command, CommandBehavior behavior) +287
   System.Data.Common.DbDataAdapter.Fill(DataSet dataSet, String srcTable) +92
   System.Web.UI.WebControls.SqlDataSourceView.ExecuteSelect(DataSourceSelectArguments arguments) +1297
   System.Web.UI.DataSourceView.Select(DataSourceSelectArguments arguments, DataSourceViewSelectCallback callback) +19
   System.Web.UI.WebControls.DataBoundControl.PerformSelect() +142
   System.Web.UI.WebControls.BaseDataBoundControl.DataBind() +73
   System.Web.UI.WebControls.GridView.DataBind() +4
   System.Web.UI.WebControls.BaseDataBoundControl.EnsureDataBound() +82
   System.Web.UI.WebControls.CompositeDataBoundControl.CreateChildControls() +72
   System.Web.UI.Control.EnsureChildControls() +87
   System.Web.UI.Control.PreRenderRecursiveInternal() +44
   System.Web.UI.Control.PreRenderRecursiveInternal() +171
   System.Web.UI.Control.PreRenderRecursiveInternal() +171
   System.Web.UI.Control.PreRenderRecursiveInternal() +171
   System.Web.UI.Control.PreRenderRecursiveInternal() +171
   System.Web.UI.Control.PreRenderRecursiveInternal() +171
   System.Web.UI.Control.PreRenderRecursiveInternal() +171
   System.Web.UI.Control.PreRenderRecursiveInternal() +171
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +842




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Version Information: Microsoft .NET Framework Version:2.0.50727.3082; ASP.NET Version:2.0.50727.3082 

Answer 1

The problem might be VS itself. In having such problems in the past, my problems have sometimes gone away with VS restart or reboot. Assuming that didn’t help:

My guess is that VS is probably fine, and the data access layer (DAL) you’re using is the problem. It seems to be trying to handle the error but not doing a very good job. I can’t tell from the stack trace, but are you referencing another .NET library for you DAL, or using a 3rd party DAL? In the first case, you should be able to run that, put in break points, and then run your top-level code. You should be able to hit your breakpoints. If this is a 3rd party DAL, that won’t work.

If you simply can not step through your DAL code, then you have to:

1. Analyze the stack trace and try to piece together what’s happening. You do have a good clue with the first line in the stack trace: something is trying to put data too big into a data structure too small. If this is a write process, then the thing-too-small is probably a field in the db — compare the data you’re working with compared to where it’s going. If this is a read process, the thing-too-small is an intermediate sql UDF or procedure.
2. Use the SQL Server Profiler to see what exactly is happening. (This assumes you’re using SQL server of course.) If you haven’t used that tool before, this is a great time to start. It will allow you to fix problems like this. Even when working with code with good error handling, this tool is great for production problems. With Profiler, you’ll be able to see the sql action happening, and see where the error is happening.