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Docs > CodeRush: IDE Productivity Extension for Visual Studio > Static Code Analysis > Analyzers Library > CRR0027 - Possible System.NullReferenceException
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CRR0001 - Redundant sub-expressions in a binary operation
CRR0002 - Suspect variable reference in a For-loop condition
CRR0003 - Suspect variable reference in the For-loop iterator section
CRR0004 - Ternary expression has identical branches
CRR0005 - Expression value is always the same
CRR0006 - Suspect variable reference in null-check following as-cast
CRR0007 - String format item/argument mismatch
CRR0008 - If-block matches else-block
CRR0009 - Subsequent if-statements have identical conditions
CRR0010 - Exception without throw
CRR0011 - Next if-statement has an identical condition that will never be reached
CRR0012 - Logical OR expression has opposite operands
CRR0013 - The member always returns the same value
CRR0014 - The variable is assigned twice in succession
CRR0015 - Logical OR expression redundancy
CRR0016 - Method call's return value is ignored
CRR0017 - Null check follows usage
CRR0018 - Suspect assignment reversal
CRR0019 - Expression contains redundant subsets
CRR0020 - Integral divide operation cast to float
CRR0021 - Subsequent else-if conditions are identical
CRR0022 - Unreachable conditional code block (a similar condition in the else branch)
CRR0023 - Unnecessary conditional
CRR0024 - Increase precision with a built-in constant or call
CRR0025 - Unreachable conditional code block (the inversed condition is already satisfied)
CRR0026 - Unused member
CRR0027 - Possible System.NullReferenceException
CRR0028 - Empty event handler
CRR0029 - The ConfigureAwait(true) is called implicitly
CRR0030 - Redundant 'await'
CRR0031 - The returned Task is null
CRR0033 - The void async method should be in a try/catch block
CRR0034 - The asynchronous method should contain the "Async" suffix
CRR0035 - No CancellationToken parameter in the asynchronous method
CRR0036 - The 'await Task.FromResult()' expression is redundant
CRR0037 - Task.Wait is used in an async method
CRR0038 - The CancellationToken parameter is never used
CRR0039 - The 'await' expression without cancellation token
CRR0041 - Use Task.Run instead of Task.Factory.StartNew
CRR0042 - Unused parameter
CRR0043 - Unused type
CRR0044 - Unused local variable
CRR0045 - Local variable can be replaced with discard
CRR0046 - Redundant field initialization
CRR0047 - The type can be moved to a separate file
CRR0048 - The type name does not correspond to the file name
CRR0049 - Environment.NewLine can be used
CRR0050 - String.Compare can be used
CRR0051 - String.IsNullOrEmpty can be used
CRR0052 - String interpolation can be used
CRR2007 - IIF function has identical result arguments
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CRR0027 - Possible System.NullReferenceException

This analyzer detects unprotected code that can potentially raise a System.NullReferenceException exception.

CodeRush checks the following elements: member’s qualifiers, collections inside of a foreach loop, collections used to call indexers.

How to Enable

Choose the Possible System.NullReferenceException issue in the Editor | Language | Code Analysis | Code Issues Catalog options page and check the Enabled checkbox.

Enable

Null Reference Analysis Modes

CodeRush can analyze values in Trusting, Skeptical, and Thorough diagnostic modes. You can specify the Possible System.NullReferenceException diagnostic mode for methods, properties, parameters, fields, and local variables. See Null Reference Analysis topic for more information about each diagnostic mode.

Customization

You can configure the Possible System.NullReferenceException diagnostic’ settings in the Editor | Language | Code Analysis | Possible NullReferenceException options page. The following screenshot shows the default settings.

Options

CodeRush also provides an option to check anonymous methods’ parameters.