NullReferenceException

Question

Okay, I've encountered a strange problem and I can't find that anyone else has encountered it here. It cropped up by accident in my environment, but it's a real issue.
We were migrating our code over to our assurance server. Unfortunately, some of the keys for some of the tables didn't get moved over, so when I ran my code and it tried to do an insert into one of these tables, I get an exception because the key doesn't exist (integrity error, yada yada).
Anyway, that's not the issue. I catch the exception, clean up the command and the connection and move on... Theoretically. The next time I try to run my service, the Odpnet DLL just completely and utterly blows up. I start getting NullReferenceExceptions all over the place, and I can't even get a stack trace back to my code. It just shows me the assembly for the oracle dll. Very frustrating.
The error I'm most frequently getting is:
Unhandled Exception: System.NullReferenceException: Object reference not set to
an instance of an object.
at Oracle.DataAccess.Types.OpsDat.FreeValCtx(OpoDatValCtx* ctx)
at Oracle.DataAccess.Types.OpoDatCtx.Dispose()
at Oracle.DataAccess.Types.OpoDatCtx.Finalize()
But, I don't always get this. Sometimes I just get what appears to be random corruption in fields.
I've verified that it has something to do with the exception. When I fix the condition that causes the exception, my code works.
Does anyone have any clue about this? It's a potential code breaker, as I can't exactly pray that my service works correctly all the time. If exceptions blow things up (even when you catch them and think you're cleaning things up) then what can you possibly do? (Yes, I've been banging my head against the wall for a while on this one)
Any help is greatly appreciated.

Answer 1

Hi again,
I isolated the problem and think I found a solution from my point of view, but I thought it might be something you'd want to look into anyway.
The problem seems to occur when I do an arraybind on a parameter specified as an OracleDbType.Date. I was essentially binding an object array of MS's DateTime type to the parameter. That works until an exception is hit, then bad things happen. A couple of things seem to work to correct this. First, binding an array declared as DateTime types (rather than object), or binding an object array of OracleDate types.
Here's some really simplistic code that demonstrates the 3 different test cases. (Sorry about the formatting, I don't really have the time to convert this into a nice pretty HTML format)
using System;
using System.Data;
using System.Collections;
using Oracle.DataAccess.Client;
using Oracle.DataAccess.Types;
namespace TestOraExceptions
/// <summary>
/// Summary description for Class1.
/// </summary>
class Test
string m_sConnString = "Data Source=GTDDEV1; User ID=****; Password=****;Min Pool Size=10;Max Pool Size=25;Connection Lifetime=340;Connection Timeout=60";
static string m_sUsage = "Specify a test to run: \n " +
"\t1 - Use array of objects of type DateTime (Causes bad things to happen)\n" +
"\t2 - Use an array declared of type DateTime (Seems to work)\n" +
"\t3 - Use array of objects of type OracleDate (Seems to work)\n";
/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
static void Main(string[] args)
if (args.Length == 0)
Console.WriteLine(m_sUsage);
return;
int iTestNum = Int32.Parse(args[0]);
if(iTestNum <= 0 || iTestNum >3)
Console.WriteLine(m_sUsage);
Test test = new Test();
switch(iTestNum)
case 1:
Console.WriteLine("Test 1");
test.runTest1();
break;
case 2:
Console.WriteLine("Test 2");
test.runTest2();
break;
case 3:
Console.WriteLine("Test 3");
test.runTest3();
break;
default:
break;
public void runTest1()
for(int i=0; i<15; i++)
generateOraException1();
public void runTest2()
for(int i=0; i<100; i++)
generateOraException2();
public void runTest3()
for(int i=0; i<100; i++)
generateOraException3();
public OracleConnection getConnection()
OracleConnection conn = null;
try
conn = new OracleConnection(m_sConnString);
conn.Open();
catch(OracleException e)
Console.WriteLine(e.Message);
return conn;
public void generateOraException1()
OracleConnection conn = getConnection();
object[] dateArray = new object[5];
for(int i=0; i<5;i++)
dateArray[i] = new DateTime(2003, 6, 2);
//Non-existant stored procedure!!! Guaranteed to generate an exception
String sStoredProcedure =
"app_mt.pk_portfolio_chars_calc2.blah_blah_blah_blah";
OracleCommand command = new OracleCommand(sStoredProcedure, conn);
command.CommandType = CommandType.StoredProcedure;
command.ArrayBindCount = dateArray.Length;
OracleParameter aDate = new OracleParameter("a_date", OracleDbType.Date);
aDate.Direction = ParameterDirection.Input;
aDate.Value = dateArray;
command.Parameters.Add(aDate);
OracleTransaction tx=null;
try
tx = conn.BeginTransaction();
command.ExecuteNonQuery();
tx.Commit();
catch (Exception e)
Console.WriteLine("Exception!");
//Console.WriteLine(e);
finally
tx.Rollback();
if (command !=null) command.Dispose();
if (conn !=null) conn.Close();
public void generateOraException2()
OracleConnection conn = getConnection();
DateTime[] dateArray = new DateTime[5];
for(int i=0; i<5;i++)
dateArray[i] = new DateTime(2003, 6, 2);
//Non-existant stored procedure!!!
String sStoredProcedure =
"app_mt.pk_portfolio_chars_calc2.blah_blah_blah_blah";
OracleCommand command = new OracleCommand(sStoredProcedure, conn);
command.CommandType = CommandType.StoredProcedure;
command.ArrayBindCount = dateArray.Length;
OracleParameter aDate = new OracleParameter("a_date", OracleDbType.Date);
aDate.Direction = ParameterDirection.Input;
aDate.Value = dateArray;
command.Parameters.Add(aDate);
OracleTransaction tx=null;
try
tx = conn.BeginTransaction();
command.ExecuteNonQuery();
tx.Commit();
catch (Exception e)
Console.WriteLine("Exception!");
//Console.WriteLine(e);
finally
tx.Rollback();
if (command !=null) command.Dispose();
if (conn !=null) conn.Close();
public void generateOraException3()
OracleConnection conn = getConnection();
object[] dateArray = new object[5];
for(int i=0; i<5;i++)
dateArray[i] = new OracleDate(2003, 6, 2);
//Non-existant stored procedure!!!
String sStoredProcedure =
"app_mt.pk_portfolio_chars_calc2.blah_blah_blah_blah";
OracleCommand command = new OracleCommand(sStoredProcedure, conn);
command.CommandType = CommandType.StoredProcedure;
command.ArrayBindCount = dateArray.Length;
OracleParameter aDate = new OracleParameter("a_date", OracleDbType.Date);
aDate.Direction = ParameterDirection.Input;
aDate.Value = dateArray;
command.Parameters.Add(aDate);
OracleTransaction tx=null;
try
tx = conn.BeginTransaction();
command.ExecuteNonQuery();
tx.Commit();
catch (Exception e)
Console.WriteLine("Exception!");
//Console.WriteLine(e);
finally
tx.Rollback();
if (command !=null) command.Dispose();
if (conn !=null) conn.Close();