getting NullReferenceException information

Posted on 2004-08-05
Last Modified: 2010-04-15
When i get a NullReferenceException or "Object reference not set to an instance of an object." exception, how do i find out what object reference was not instantiated?

Question by:3Mann

Accepted Solution

AnnamalaiSwamy earned 50 total points
ID: 11733800
Catch the NullReferenceException by try...catch block and get more information about uninstantiated object through "Source" property of NullReferenceException object.


  some error
}catch(NullReferenceException e)
    msg = e.source;   //gives more details
LVL 20

Assisted Solution

TheAvenger earned 50 total points
ID: 11733801
You should have a look at the StackTrace of the exception and thus find the line where the exception occured. Then debug the application by putting a break point on that line and when the application reaches the point, you can see the values of all variables used there - see which is null.

Assisted Solution

Daeljan earned 50 total points
ID: 11736666
Also dont forget to unroll inner exceptions to get as much info as possible:

assuming 'e' is the System.Exception

// examine:       e.Message, e.StackTrace

System.Exception innerE = e.InnerException;
while (innerE != null)
    // examine:       e.Message, e.StackTrace
    innerE = innerE.InnerException;

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