Our website uses cookies to enhance your browsing experience.
Accept
to the top
close form

Fill out the form in 2 simple steps below:

Your contact information:

Step 1
Congratulations! This is your promo code!

Desired license type:

Step 2
Team license
Enterprise license
** By clicking this button you agree to our Privacy Policy statement
close form
Request our prices
New License
License Renewal
--Select currency--
USD
EUR
* By clicking this button you agree to our Privacy Policy statement

close form
Free PVS‑Studio license for Microsoft MVP specialists
* By clicking this button you agree to our Privacy Policy statement

close form
To get the licence for your open-source project, please fill out this form
* By clicking this button you agree to our Privacy Policy statement

close form
I am interested to try it on the platforms:
* By clicking this button you agree to our Privacy Policy statement

close form
check circle
Message submitted.

Your message has been sent. We will email you at


If you haven't received our response, please do the following:
check your Spam/Junk folder and click the "Not Spam" button for our message.
This way, you won't miss messages from our team in the future.

>
>
>
V3100. NullReferenceException is possib…
menu mobile close menu
Analyzer diagnostics
General Analysis (C++)
General Analysis (C#)
General Analysis (Java)
Micro-Optimizations (C++)
Diagnosis of 64-bit errors (Viva64, C++)
Customer specific requests (C++)
MISRA errors
AUTOSAR errors
OWASP errors (C#)
Problems related to code analyzer
Additional information
toggle menu Contents

V3100. NullReferenceException is possible. Unhandled exceptions in destructor lead to termination of runtime.

May 17 2016

The analyzer detected a block of code that may lead to raising a NullReferenceException in a class destructor (finalizer) when executed.

The body of a class destructor is a critical spot of the program. Starting with .NET version 2.0, throwing an unhandled exception in the destructor body will cause it to crash. An exception that has left the destructor cannot be handled afterwards.

What follows from this explanation is that when addressing objects inside a destructor, you should test them for null in advance to avoid a crash.

Consider the following example:

class A
{
  public List<int> numbers { get; set; }
  ~A()
  {
    if (numbers.Count > 0) { 
      ....
    }
  }
}

Since the 'numbers' collection was not initialized at declaration time, the 'numbers' field is not guaranteed to contain the reference to the object of class 'A' when this object is finalized. Therefore, we should additionally test the collection for null or wrap the call to the field into a try/catch block.

A correct version of the code above should look like this:

~A()
{
  if (numbers != null)
  {
    if (numbers.Count > 0)
    {
       ....
    }
  }
}

Starting with C# version 6.0, you can use the '?.' operator to reduce the check to the following code:

~A()
{
  if (numbers?.Count > 0) { 
    ....
  }
}

This diagnostic is classified as: