You are writing a web application and you decide to alter your global.asx file. When you try to debug this application you find you can an error in the code below.


protected void Application_Start(Object sender, EventArgs e)
{
Application["AppplicationCount"] = 0;
Application["SessionCount"] = 0;
Application["AppplicationCount"] = (int)Application["AppplicationCount"] + 1;
                     
}

protected void Session_Start(Object sender, EventArgs e)
{
Application["SessCount"] = (int)Application["SessCount"]+1;
Response.Write("Number of Applications: " +
Application["AppplicationCount"] + "< /br>");
Response.Write("Number of Sessions: " +
Application["SessCount"] + "< /br>");
}

Error:

Object reference not set to an instance of an object.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

Source Error:

Line 32:                                   protected void Session_Start(Object sender, EventArgs e) Line 33:                                   { Line 34:                                                    Application["SessCount"] = (int)Application["SessCount"] + 1; Line 35:                                                    Response.Write("Number of applications: " + Line 36:                                                    Application["AppCount"] + "< /br>");

Solution:

The problem is that we are referencing an object that doesn't exist or is out of scope. The problem here was an Application variable SessionCount was spelt wrong in the Session_Start method. It was Application["SessCount"] when it should have been Application["SessionCount"]