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.

>
>
>
V3146. Possible null dereference. A met…
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

V3146. Possible null dereference. A method can return default null value.

Oct 07 2019

The analyzer has detected a case of unsafe use of the value returned by one of the methods of the System.Enumerable library that can return a 'default' value.

'FirstOrDefault', 'LastOrDefault', 'SingleOrDefault', and 'ElementAtOrDefault' are examples of such methods. They return a default value if the array they are called on does not contain any object satisfying the search predicate parameter. An empty (null) reference is the default value for reference types. Therefore, a reference returned by such a method should be checked for null before it can be used.

Example of unsafe dereferencing:

public void TestMemberAccess(List<string> t)
{
    t.FirstOrDefault(x => x == "Test message").ToString(); 
}

This code requires a null check for the element returned by the method:

public void TestMemberAccess(List<string> t)
{
    t.FirstOrDefault(x => x == "Test message")?.ToString(); 
}

Methods returning default values are especially dangerous when used in call chains. This is an example from one open-source project:

public IViewCompiler GetCompiler()
{
  ....
  _compiler = _services
    .GetServices<IViewCompilerProvider>()
    .FirstOrDefault()
    .GetCompiler();
  }
  ....
  return _compiler;
}

If you are sure that the array contains the required element, we recommend using a method that does not return a default value:

public IViewCompiler GetCompiler()
{
  ....
  _compiler = _services
    .GetServices<IViewCompilerProvider>()
    .First()
    .GetCompiler();
  }
  ....
  return _compiler;
}

With this fix, if an error occurs, the program will throw an 'InvalidOperationException' with a more intelligible message "Sequence contains no elements" rather than a 'NullReferenceException'.

This diagnostic is classified as:

You can look at examples of errors detected by the V3146 diagnostic.