Clear-Variable with wildcard attempts to clear read-only system constants and automatic variables #25769

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Clear-Variable with wildcard attempts to clear read-only system constants and automatic variables#25769

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Needs-TriageWG-CmdletsWG-NeedsReview

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on Jul 21, 2025

Prerequisites

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Make sure you are able to repro it on the latest released version
Search the existing issues.
Refer to the FAQ.
Refer to Differences between Windows PowerShell 5.1 and PowerShell.

Steps to reproduce

Run in any PowerShell 7+ session

Clear-Variable *

Expected behavior

Clear-Variable * should automatically skip all variables with ReadOnly or Constant options set. System variables like $true, $false, $Error, and $PSStyle should be silently filtered out before any clear operation is attempted. Only user-defined, modifiable variables should be processed.

Actual behavior

The cmdlet attempts to clear ALL variables including immutable system constants and automatic variables, resulting in predictable and non-actionable errors:

Clear-Variable: Cannot overwrite variable false because it is read-only or constant.
Clear-Variable: Cannot overwrite variable true because it is read-only or constant.
Clear-Variable: Cannot overwrite variable Error because it is read-only or constant.
Clear-Variable: Cannot overwrite variable PSStyle because it is read-only or constant.
Clear-Variable: Cannot convert null to type "System.Management.Automation.ConfirmImpact" due to enumeration values that are not valid. Specify one of the following enumeration values and try again. The possible enumeration values are "None,Low,Medium,High".

Error details

Get-Error | Select-Object -First 1 | Format-List *
irst 1 | Format-List *Clear-Variable: 
Line |
   5 |  Clear-Variable *
     |  ~~~~~~~~~~~~~~~~
     | Cannot overwrite variable false because it is read-only or constant.
Clear-Variable: 
Line |
   5 |  Clear-Variable *
     |  ~~~~~~~~~~~~~~~~
     | Cannot overwrite variable true because it is read-only or constant.
Clear-Variable: 
Line |
   5 |  Clear-Variable *
     |  ~~~~~~~~~~~~~~~~
     | Cannot overwrite variable Error because it is read-only or constant.
Clear-Variable: 
Line |
   5 |  Clear-Variable *
     |  ~~~~~~~~~~~~~~~~
     | Cannot overwrite variable PSStyle because it is read-only or constant.
Clear-Variable: 
Line |
   5 |  Clear-Variable *
     |  ~~~~~~~~~~~~~~~~
     | Cannot convert null to type "System.Management.Automation.ConfirmImpact" due to enumeration values that are not valid. Specify one of the following enumeration values and try again. The possible enumeration values are "None,Low,Medium,High".

Exception             : System.Management.Automation.ArgumentTransformationMetadataException: Cannot convert null to type "System.Management.Automation.ConfirmImpact" due to enumeration values that are not valid. S 
                        pecify one of the following enumeration values and try again. The possible enumeration values are "None,Low,Medium,High".
                         ---> System.Management.Automation.PSInvalidCastException: Cannot convert null to type "System.Management.Automation.ConfirmImpact" due to enumeration values that are not valid. Specify one  
                        of the following enumeration values and try again. The possible enumeration values are "None,Low,Medium,High".
                           at System.Management.Automation.LanguagePrimitives.ThrowInvalidCastException(Object valueToConvert, Type resultType)
                           at System.Management.Automation.LanguagePrimitives.ConvertNoConversion(Object valueToConvert, Type resultType, Boolean recurse, PSObject originalValueToConvert, IFormatProvider formatProv
                        ider, TypeTable backupTable)
                           at System.Management.Automation.LanguagePrimitives.ConvertTo(Object valueToConvert, Type resultType, Boolean recursion, IFormatProvider formatProvider, TypeTable backupTypeTable)
                           at System.Management.Automation.ArgumentTypeConverterAttribute.Transform(EngineIntrinsics engineIntrinsics, Object inputData, Boolean bindingParameters, Boolean bindingScriptCmdlet)       
                           --- End of inner exception stack trace ---
                           at System.Management.Automation.ArgumentTypeConverterAttribute.Transform(EngineIntrinsics engineIntrinsics, Object inputData, Boolean bindingParameters, Boolean bindingScriptCmdlet)       
                           at System.Management.Automation.ArgumentTypeConverterAttribute.Transform(EngineIntrinsics engineIntrinsics, Object inputData)
                           at System.Management.Automation.PSVariable.TransformValue(IEnumerable`1 attributes, Object value)
                           at System.Management.Automation.PSVariable.SetValue(Object value)
                           at System.Management.Automation.SessionStateScope.SetVariable(String name, Object value, Boolean asValue, Boolean force, SessionStateInternal sessionState, CommandOrigin origin, Boolean f 
                        astPath)
                           at System.Management.Automation.SessionStateInternal.SetVariable(VariablePath variablePath, Object newValue, Boolean asValue, Boolean force, CommandOrigin origin)
                           at System.Management.Automation.SessionStateInternal.SetVariableValue(String name, Object newValue, CommandOrigin origin)
                           at Microsoft.PowerShell.Commands.ClearVariableCommand.ClearValue(PSVariable matchingVariable)
                           at Microsoft.PowerShell.Commands.ClearVariableCommand.ProcessRecord()
                           at System.Management.Automation.CommandProcessor.ProcessRecord()
TargetObject          : 
CategoryInfo          : MetadataError: (:) [Clear-Variable], ArgumentTransformationMetadataException
FullyQualifiedErrorId : RuntimeException,Microsoft.PowerShell.Commands.ClearVariableCommand
ErrorDetails          : 
InvocationInfo        : System.Management.Automation.InvocationInfo
ScriptStackTrace      : at <ScriptBlock>, <No file>: line 5
PipelineIterationInfo : {}


Exception             : System.Management.Automation.ArgumentTransformationMetadataException: Cannot convert null to type "System.Management.Automation.ConfirmImpact" due to enumeration values that are not valid. S 
                        pecify one of the following enumeration values and try again. The possible enumeration values are "None,Low,Medium,High".
                         ---> System.Management.Automation.PSInvalidCastException: Cannot convert null to type "System.Management.Automation.ConfirmImpact" due to enumeration values that are not valid. Specify one  
                        of the following enumeration values and try again. The possible enumeration values are "None,Low,Medium,High".
                           at System.Management.Automation.LanguagePrimitives.ThrowInvalidCastException(Object valueToConvert, Type resultType)
                           at System.Management.Automation.LanguagePrimitives.ConvertNoConversion(Object valueToConvert, Type resultType, Boolean recurse, PSObject originalValueToConvert, IFormatProvider formatProv 
                        ider, TypeTable backupTable)
                           at System.Management.Automation.LanguagePrimitives.ConvertTo(Object valueToConvert, Type resultType, Boolean recursion, IFormatProvider formatProvider, TypeTable backupTypeTable)
                           at System.Management.Automation.ArgumentTypeConverterAttribute.Transform(EngineIntrinsics engineIntrinsics, Object inputData, Boolean bindingParameters, Boolean bindingScriptCmdlet)       
                           --- End of inner exception stack trace ---
                           at System.Management.Automation.ArgumentTypeConverterAttribute.Transform(EngineIntrinsics engineIntrinsics, Object inputData, Boolean bindingParameters, Boolean bindingScriptCmdlet)       
                           at System.Management.Automation.ArgumentTypeConverterAttribute.Transform(EngineIntrinsics engineIntrinsics, Object inputData)
                           at System.Management.Automation.PSVariable.TransformValue(IEnumerable`1 attributes, Object value)
                           at System.Management.Automation.PSVariable.SetValue(Object value)
                           at System.Management.Automation.SessionStateScope.SetVariable(String name, Object value, Boolean asValue, Boolean force, SessionStateInternal sessionState, CommandOrigin origin, Boolean f 
                        astPath)
                           at System.Management.Automation.SessionStateInternal.SetVariable(VariablePath variablePath, Object newValue, Boolean asValue, Boolean force, CommandOrigin origin)
                           at System.Management.Automation.SessionStateInternal.SetVariableValue(String name, Object newValue, CommandOrigin origin)
                           at Microsoft.PowerShell.Commands.ClearVariableCommand.ClearValue(PSVariable matchingVariable)
                           at Microsoft.PowerShell.Commands.ClearVariableCommand.ProcessRecord()
                           at System.Management.Automation.CommandProcessor.ProcessRecord()
TargetObject          : 
CategoryInfo          : MetadataError: (:) [Clear-Variable], ArgumentTransformationMetadataException
FullyQualifiedErrorId : RuntimeException,Microsoft.PowerShell.Commands.ClearVariableCommand
ErrorDetails          : 
InvocationInfo        : System.Management.Automation.InvocationInfo
ScriptStackTrace      : at <ScriptBlock>, <No file>: line 5
PipelineIterationInfo : {}

Environment data

$PSVersionTable

Name                           Value
----                           -----
PSVersion                      7.5.2
PSEdition                      Core
GitCommitId                    7.5.2
OS                             Microsoft Windows 10.0.19045
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0

Visuals

Get-Variable true, false, Error, PSStyle | Select-Object Name, Options

Let's check what variables DON'T have ReadOnly or Constant set

Get-Variable * | Where-Object {
-not ($.Options -band [System.Management.Automation.ScopedItemOptions]::ReadOnly) -and
-not ($.Options -band [System.Management.Automation.ScopedItemOptions]::Constant)
} | Select-Object Name, Options

Or more clearly, let's see which variables are causing issues

Get-Variable * | Where-Object {
$_.Options -match 'ReadOnly|Constant'
} | Select-Object Name, Options

Find variables that might have the ConfirmImpact type

Get-Variable * | Where-Object {
$_.Value -is [System.Management.Automation.ConfirmImpact]
} | Select-Object Name, Value, Options

Name Options

true Constant, AllScope
false Constant, AllScope
Error Constant
PSStyle Constant
^ None
$ None
args None
AvailableLayers None
ConfirmPreference None
DebugPreference None
ErrorActionPreference None
ErrorView None
FormatEnumerationLimit None
InformationPreference None
input None
Matches None
MaximumHistoryCount None
MyInvocation None
NestedPromptLevel None
null None
OutputEncoding None
PROFILE None
ProgressPreference None
PSBoundParameters None
PSCommandPath None
PSDefaultParameterValues None
PSEmailServer None
PSNativeCommandArgumentPassing None
PSNativeCommandUseErrorActionPreference None
PSScriptRoot None
PSSessionApplicationName None
PSSessionConfigurationName None
PSSessionOption None
PWD None
StackTrace None
VerbosePreference None
WarningPreference None
WhatIfPreference None
? ReadOnly, AllScope
EnabledExperimentalFeatures Constant, AllScope
Error Constant
ExecutionContext Constant, AllScope
false Constant, AllScope
HOME ReadOnly, AllScope
Host Constant, AllScope
IsCoreCLR ReadOnly, AllScope
IsLinux ReadOnly, AllScope
IsMacOS ReadOnly, AllScope
IsWindows ReadOnly, AllScope
PID Constant, AllScope
PSCulture ReadOnly, AllScope
PSEdition Constant, AllScope
PSHOME Constant, AllScope
PSStyle Constant
PSUICulture ReadOnly, AllScope
PSVersionTable Constant, AllScope
ShellId Constant, AllScope
true Constant, AllScope
ConfirmPreference None

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