exception of type 'System.NullReferenceException' occurred in logindemo.dll but was not handled in user code

In logindemo class, some object might not be created using new operator.
You might have set that object to null, but using it later, without actually creating it(using new). Share the code to identify the bug

Your code should be able to handle the exceptions. Please add code to Catch the exception. The see from where the issue occurs in the stack trace. and see for which reference an object is not created and is null.