Object Reference Null in Connection Property ?

Question

1.00/5 (1 vote)

See more:

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=");

C#

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 13:51pm

kashifjaat

Add a Solution

Comments

ZurdoDev 26-Feb-13 19:53pm

What's the exact error and which line of code is it?

Jibesh 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 26-Feb-13 20:27pm

In what line?
—SA

[no name] 27-Feb-13 11:05am

What is the error.?

2 solutions

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Sergey Alexandrovich Kryukov · Accepted Answer · 2013-02-26T14:28:00

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

kashifjaat · Accepted Answer · 2013-02-27T01:35:00

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...

Posted 27-Feb-13 1:35am