AvoidNullOrEmptyHelpMessageAttribute.md

description	Avoid using null or empty HelpMessage parameter attribute
ms.date	07/21/2026
ms.topic	reference
title	AvoidNullOrEmptyHelpMessageAttribute

AvoidNullOrEmptyHelpMessageAttribute

Severity Level: Warning

Default state: Always enabled

Description

This rule detects HelpMessage attributes that contain null values, empty strings, or no value assignment. The HelpMessage attribute must contain a meaningful, non-empty string value. Omitting the value altogether causes a parse-time syntax error.

Using an empty string or null value causes PowerShell to raise an error at runtime. Always provide a descriptive help message that explains the parameter's purpose and expected input to users.

Example

Noncompliant

Function BadFuncEmptyHelpMessageEmpty
{
    Param(
        [Parameter(HelpMessage='')]
        [String]
        $Param
    )

    $Param
}

Function BadFuncEmptyHelpMessageNull
{
    Param(
        [Parameter(HelpMessage=$null)]
        [String]
        $Param
    )

    $Param
}

Function BadFuncEmptyHelpMessageNoAssignment
{
    Param(
        [Parameter(HelpMessage)]
        [String]
        $Param
    )

    $Param
}

Compliant

Function GoodFuncHelpMessage
{
    Param(
        [Parameter(HelpMessage='This is helpful')]
        [String]
        $Param
    )

    $Param
}

Configure rule

This rule is always enabled and isn't configurable. Use one of the following methods to avoid using this rule:

• Create a custom rule configuration file to include only the rules you want or exclude the rules you don't want.
• Add the appropriate rule suppression attributes to your code to suppress the rule for specific code blocks. For more information, see the Suppressing rules section of Using PSScriptAnalyzer.