Start-ThreadJob doesn't honor switches or preference variables for Write-Debug, Write-Verbose, Write-Information

[jimAtLoyal]

Prerequisites

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Steps to reproduce

Start-ThreadJob doesn't produce output for Information, Verbose, Debug in most cases. Here's a trivial test

Start-ThreadJob -ScriptBlock {
    $InformationPreference='Continue'
    $VerbosePreference='Continue'
    $DebugPreference='Continue'
    
    Write-Host "Starting test"

    Write-Information "Write-Information -InformationAction Continue" -InformationAction Continue
    Write-Information "Write-Information"

    Write-Verbose "Write-Verbose -Verbose" -Verbose
    Write-Verbose "Write-Verbose"

    Write-Debug "Write-Debug -Debug" -Debug
    Write-Debug "Write-Debug"
} | Receive-Job -Wait -AutoRemoveJob

Using Start-Job works. It appears to be that the thread job will only use the preferences variable from the caller, but ignore ones within the script or the switches.

The workaround is to set variables in the calling instance before calling Start-ThreadJob

$InformationPreference='Continue'
$VerbosePreference='Continue'
$DebugPreference='Continue'
Start-ThreadJob ...

This may be related to #24016

Expected behavior

Starting test
Write-Information -InformationAction Continue
Write-Information
VERBOSE: Write-Verbose -Verbose
VERBOSE: Write-Verbose
DEBUG: Write-Debug -Debug
DEBUG: Write-Debug

Actual behavior

Starting test

Error details

Environment data

Name                           Value
----                           -----
PSVersion                      7.5.4
PSEdition                      Core
GitCommitId                    7.5.4
OS                             Darwin 24.6.0 Darwin Kernel Version 24.6.0: Mon Jul 14 11:30:29 PDT 2025; root:xnu-11417.140.69~1/RELEASE_ARM64_T6000
Platform                       Unix
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0

Visuals

No response

[jimAtLoyal]

I found that in a function, you must inject the preference variable. Calling test -Verbose only writes the second line. Setting $VerbosePreference='Continue before calling test doesn't make a difference.

function test {
    [CmdletBinding()] param()
    Start-ThreadJob -ScriptBlock { Write-Verbose "Write-Verbose doesn't work" } | Receive-Job -Wait -AutoRemoveJob
    Start-ThreadJob -ScriptBlock { $VerbosePreference=$using:VerbosePreference; Write-Verbose "Write-Verbose works" } | Receive-Job -Wait -AutoRemoveJob
}

[mklement0]

Indeed, it seems that the summary in #24016 (comment) still applies.