Powershell Mechanical Fixups

PowerShell Mechanical Fix-ups (5.1 → 7.x)

Deterministic rewrites for the AutoFix-severity findings from the scanning-powershell-compatibility scan. Apply these first: they are low-risk and shrink the noise before the architectural blockers.

Fixes

1. -Encoding Byte → -AsByteStream

Get-Content/Set-Content dropped the Byte encoding value in PS7.

# 5.1
Get-Content $path -Encoding Byte
Set-Content $path -Encoding Byte -Value $bytes
# 7.x
Get-Content $path -AsByteStream
Set-Content $path -AsByteStream -Value $bytes

If the script also passes -Raw, keep it. -AsByteStream already returns the raw byte array.

2. Hardcoded powershell.exe → pwsh

powershell.exe always launches Windows PowerShell 5.1. Use pwsh to invoke PowerShell 7. Watch for:

• Nested invocations: Start-Process powershell.exe, & 'powershell.exe', scheduled-task actions, Invoke-Command.
• Do not blindly change paths that intentionally target 5.1 (rare — call it out and confirm).

3. Remove New-WebServiceProxy

Removed in PS7. Replace with Invoke-RestMethod/Invoke-WebRequest against the endpoint, or a generated WCF client. This is not purely mechanical — flag each call site for the SOAP/REST replacement decision.

4. #Requires version pin

#Requires -Version states a minimum, so #Requires -Version 5.1 does not block PowerShell 7 — the script still runs. It is stale metadata worth correcting, not a blocker. #Requires -PSEdition Desktop is a blocker: PowerShell 7 is edition Core and refuses to run the script at all.

Once a script is PS7-clean, update the directive. Use 7.0 as the floor — it is the edition gate (any PowerShell 7 is Core/.NET), not a pin to a specific minor. Only raise the floor above 7.0 if the script actually uses a feature introduced in a later 7.x:

# 5.1
#Requires -Version 5.1
#Requires -PSEdition Desktop
# 7 (Core)
#Requires -Version 7.0
# (drop -PSEdition Desktop; add -PSEdition Core only if truly Core-only)

Bump the version after the script passes validation, not before. Raising the floor is what stops the script silently regressing back onto Windows PowerShell.

5. Pin -Encoding on file writes

The highest-impact silent break in this migration, and the one no parse or compatibility rule will catch: the default output encoding changed. The script keeps running and the bytes on disk change.

Measured on 5.1 and 7.6 with the literal content abc; do not restate this table from memory, it is counter-intuitive. The redirection operators and Out-File are not ANSI in 5.1 — treating them as ANSI is the single most damaging mistake available here, because it is the highest-volume finding class.

Consequences to look for: a downstream tool that reads the file with the system code page now sees mojibake for non-ASCII text; a consumer that requires a BOM (some Windows tooling, Excel opening a CSV) no longer finds one; and a file compared byte-for-byte in a test now differs.

The fix is to make the encoding explicit rather than to adopt the new default:

# implicit — meaning changes between 5.1 and 7
$data | Set-Content $path
$data | Out-File $path -Encoding UTF8       # BOM in 5.1, no BOM in 7

# explicit — same bytes on both
$data | Set-Content $path -Encoding utf8BOM   # or: ansi / utf8NoBOM / unicode
$data | Out-File     $path -Encoding unicode  # reproduces the 5.1 bytes exactly

> and >> take no -Encoding; a site that must keep its 5.1 bytes has to be rewritten as | Out-File -Encoding unicode.

Pin whatever the consumer needs, not whatever the script used to emit by accident. utf8NoBOM is the right answer for anything Git-tracked or read by cross-platform tooling; utf8BOM for legacy Windows consumers. For an Out-File/redirection site whose consumer is unknown, unicode is the byte-preserving choice — ansi is not, and never was. $PSDefaultParameterValues can set it once per script, but an explicit parameter at each call site survives refactoring better.

Note -Encoding ansi and utf8BOM/utf8NoBOM are PS7-only spellings; if a script must run under both editions, use -Encoding values that exist in both (ascii, unicode, utf7, utf8, utf32, bigendianunicode, oem) and accept that utf8 differs on BOM.

6. Fragile $null comparison

$x -eq $null unrolls arrays and misbehaves. Rewrite with $null on the left:

if ($x -eq $null)  →  if ($null -eq $x)
if ($x -ne $null)  →  if ($null -ne $x)

This is Advisory, not a completion gate — offer it as an optional batch. Be careful not to rewrite matches inside strings/comments.

Validation

After applying, re-run the scanning-powershell-compatibility scan on the touched files to confirm the AutoFix findings cleared, then climb the scenario's validation ladder (parse → PSScriptAnalyzer).