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Error Object Refference Null :- I use This Connection
con = new OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=D:\MIS SYSTEM\AniPharmic\AniPharmic\MedicalDb.accdb;Jet OLEDB:Database Password=");
 
try
           {
 

 

 
               con.Open();
               str = "select *from DatabaseLogin where user_id='" + textBox2.Text + "'";
               com = new OleDbCommand(str, con);
               OleDbDataReader reader = com.ExecuteReader();
               while (reader.Read())
               {
                   checkedListBox1.Items.Add(reader["stckdemge"]);
               }
 

 
           }
           catch (Exception ex)
           {
               MessageBox.Show(" " + ex);
           }
Posted 26-Feb-13 14:51pm
Comments
ryanb31 at 26-Feb-13 19:53pm
   
What's the exact error and which line of code is it?
Jibesh at 26-Feb-13 20:16pm
   
Null reference error are easy to catch. run your application and debug mode and put a break point at the code where you find causing the exception thats all. you find the reason for the exception.
 
If you still have no clue paste the complete exception stack.
Sergey Alexandrovich Kryukov at 26-Feb-13 20:27pm
   
In what line?
—SA
Hrushikesh_phapale at 27-Feb-13 11:05am
   
What is the error.?
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Solution 1

You did not show where the exception with the message "Object reference not set to an instance of an object" is thrown.

Not to worry. This is one of the very easiest cases to detect and fix. It simply means that some member/variable of some reference type is dereferenced by using and of its instance (non-static) members, which requires this member/variable to be non-null, but in fact it appears to be null. Simply execute it under debugger, it will stop the execution where the exception is thrown. Put a break point on that line, restart the application and come to this point again. Evaluate all references involved in next line and see which one is null while it needs to be not null. After you figure this out, fix the code: wither make sure the member/variable is properly initialized to a non-null reference, or check it for null and, in case of null, do something else.
 
Please see also: want to display next record on button click. but got an error in if condition of next record function "object reference not set to an instance of an object"[^].
 
Good luck,
—SA
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Solution 2

Error is In this Line
 

4- con.Open();

Error is :- Cannot open Connection:System.NullReferenceException:Object Reference Not
set to an instance of an object.


 
its not problem in other form its only prroblem in this code...
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