PowerShell 5.1 and 7: the runtime is part of the job

Installing PowerShell 7 does not automatically change existing script invocations. Windows PowerShell 5.1 starts through powershell.exe, while PowerShell 7 uses pwsh.exe. Both can coexist while a scheduled task continues to use its previous runtime. Microsoft: Migrating to PowerShell 7.

Identify the runtime where the job executes

The following query belongs inside the actual job, for example as temporary diagnostic output from a scheduled task. It also records the executing account, whose permissions can affect the result.

[pscustomobject]@{
    Version = $PSVersionTable.PSVersion.ToString()
    Edition = $PSVersionTable.PSEdition
    Process = (Get-Process -Id $PID).Path
    Account = [Security.Principal.WindowsIdentity]::GetCurrent().Name
    Is64Bit = [Environment]::Is64BitProcess
}

Under 5.1, Edition reports Desktop. Under 7, it reports Core. The process path and architecture help identify differences between invocations. A check in an administrator's own terminal confirms only that environment.

Compare the same script result under 5.1 and 7

A small inventory script provides a starting point. Saved as Inventory.ps1, it reads the local computer name and the operating system's caption and version. It changes no system settings and returns the selected fields as JSON.

$ErrorActionPreference = 'Stop'
Get-CimInstance -ClassName Win32_OperatingSystem |
    Select-Object CSName, Caption, Version |
    ConvertTo-Json -Compress

Run the following on the same Windows computer from the directory containing the file. Both PowerShell versions must be available through PATH. -NoProfile excludes personal profile customizations, while -NonInteractive prevents interactive prompts.

$ErrorActionPreference = 'Stop'
$ps51 = & powershell.exe -NoProfile -NonInteractive -File .\Inventory.ps1
if ($LASTEXITCODE -ne 0) { throw 'Windows PowerShell failed.' }

$ps7 = & pwsh.exe -NoProfile -NonInteractive -File .\Inventory.ps1
if ($LASTEXITCODE -ne 0) { throw 'PowerShell 7 failed.' }

Compare-Object ($ps51 | ConvertFrom-Json) ($ps7 | ConvertFrom-Json) `
    -Property CSName, Caption, Version -CaseSensitive

No output means the three compared values match. Differences appear with <= for the 5.1 side and => for the 7 side. This checks the selected data after JSON conversion, not the original .NET object types. Microsoft: Compare-Object.

For an existing script, testing also needs to cover module versions, missing access rights and unreachable targets. File output additionally requires a comparison of format and encoding. A successful run alone does not cover these cases.

Modules loaded through Import-Module -UseWindowsPowerShell need particular attention. They run in a local Windows PowerShell 5.1 background session. Serialization can strip methods from returned objects even when reading their properties still works. A successful import therefore does not establish script compatibility. Microsoft: Windows PowerShell Compatibility.

Select the remote endpoint explicitly

With remoting over WinRM, the endpoint determines the remote runtime. The following example requires an already registered PowerShell.7 endpoint, reachable WinRM and the necessary access rights. Replace srv-app01 with the intended test host.

Invoke-Command -ComputerName 'srv-app01' `
    -ConfigurationName 'PowerShell.7' -ErrorAction Stop `
    -ScriptBlock { $PSVersionTable.PSVersion.ToString() }

The expected result is a version number in the 7.x series. Starting pwsh.exe locally is insufficient. Setup takes place on the target through Enable-PSRemoting, run from the intended PowerShell version with administrator rights. This also configures WinRM and firewall rules. Microsoft: Enable-PSRemoting.

In NodePilot, the engine setting applies only to local script steps:

Execution	Runtime used
Local, engine: auto	Windows PowerShell 5.1 by default
Local, engine: powershell	Windows PowerShell 5.1 explicitly
Local, engine: pwsh	Separate PowerShell 7 process, installation required
Local, engine: runspace	Embedded PowerShell 7 with restrictions on module use
Remote through NodePilot	Currently Windows PowerShell 5.1 through Microsoft.PowerShell

The remoting example therefore shows an independent PowerShell invocation. Installing PowerShell 7 on the target does not change remote execution in NodePilot. The Activity reference provides the details.