Object reference not set to an instance of an object. Error IN C# aspx page

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Hello,

I am getting this error but I don't know how to solve this

Object reference not set to an instance of an object.

VB

[NullReferenceException: Object reference not set to an instance of an object.]
   System.Xml.XmlLoader.Load(XmlDocument doc, XmlReader reader, Boolean preserveWhitespace) +24

I have a aspx page which contains a master page having telerik RadMenu whose datasource is defined in Masterpage cs file something like this

if (!IsPostBack)
{

C#

if (Session["MenuXML"] != null)
              xmlDataSource.Data = Session["MenuXML"].ToString();

}
}

xmlDataSource is the name of RadMenu is aspx file and I have stored xml in this session some thing like this

XML

<Menus>
      <Menu>
        <MenuID>3</MenuID>
        <Text>    Book</Text>
        <Navigate>#</Navigate>
        <Menu>
          <MenuID>51</MenuID>
          <Text>  Hotel Search</Text>
          <Navigate>Search.aspx</Navigate>
          <ParentID>3</ParentID>
        </Menu>
    <Menu>
    this tag repeating itself......
    </Menu>

</Menus>

My page works completely fine but as I do some random stuff by clicking a butting or paging the grid in aspx file then onlu some times I get this error not every time

Posted 29-Apr-14 22:00pm

Member 8680235

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Kornfeld Eliyahu Peter 30-Apr-14 4:03am

Try step-by-step debug and see which variable is null...

Member 8680235 30-Apr-14 4:44am

I did try to debug step by step by pressing F10 in VS-2010 but it passes through all the events and then page shows this error therefore I am unable to get where the error is thrown

[no name] 30-Apr-14 9:04am

You need to debug using a debug build of your website.

Member 8680235 30-Apr-14 9:13am

I am debugging in debug mode not in Release mode but still it does not throws exception in VS-2010 but page show this exception

Kornfeld Eliyahu Peter 30-Apr-14 10:05am

I saw from one of your response that you are using telerik's components. Try telerik's support - they are good...

2 solutions

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Sergey Alexandrovich Kryukov · Answer 1 · 2014-04-29T22:05:00

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: either 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"[^].

Sometimes, you cannot do it under debugger, by one or another reason. One really nasty case is when the problem is only manifested if software is built when debug information is not available. In this case, you have to use the harder way. First, you need to make sure that you never block propagation of exceptions by handling them silently (this is a crime of developers against themselves, yet very usual). The you need to catch absolutely all exceptions on the very top stack frame of each thread. You can do it if you handle the exceptions of the type System.Exception. In the handler, you need to log all the exception information, especially the System.Exception.StackTrace:
http://msdn.microsoft.com/en-us/library/system.exception.aspx[^],
http://msdn.microsoft.com/en-us/library/system.exception.stacktrace.aspx[^].

The stack trace is just a string showing the full path of exception propagation from the throw statement to the handler. By reading it, you can always find ends. For logging, it's the best (in most cases) to use the class System.Diagnostics.EventLog:
http://msdn.microsoft.com/en-us/library/system.diagnostics.eventlog.aspx[^].

Good luck,

—SA

bluesathish · Answer 2 · 2014-04-29T23:56:00

Solution 2

Hi,

Debug using F11 was a better choice in this case, It'll look into the inner functions which causes this error. This error occurs when you try to use a disposed object or one of your object didn't properly initialised. Debug line by line, you'll able to capture the root cause.

Regards,
BlueSathish

Posted 29-Apr-14 23:56pm

bluesathish

Comments

Member 8680235 30-Apr-14 6:09am

I did try to debug step by step by pressing F10 and F11 in VS-2010 but it passes through all the events and then page shows this error therefore I am unable to get where the error is thrown

Member 8680235 30-Apr-14 6:11am

Visual studio does not shows any exception but page shows the exception can you please tell me where the error is generated using stack trace??