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$? lies about native commands; check $LASTEXITCODE

exit codes · case

bothsilentscriptciagentthird-partyrepro: verifiedexit-code-propagation
Affectspowershell 51, pwsh 7, actions runner
Fails assilent
Mechanismexit code propagation
Safe fixlastexitcode gate

Symptom

Section titled “Symptom”

A pipeline keeps going after a native command failed. CI stays green while the build inside it broke. Nothing threw, nothing stopped — the failure was simply never observed.

Repro

Section titled “Repro”
Terminal window
git clone https://example.invalid/nope.git
if ($?) { "looks fine" }        # may print despite the failure in some shapes
"exit was: $LASTEXITCODE"       # 128 — the only honest signal
deploy-something                 # runs anyway

Cause

Section titled “Cause”

PowerShell’s error machinery ($?, try/catch, $ErrorActionPreference) is built around cmdlets and ErrorRecords. Native commands communicate failure through exit codes, which PowerShell before 7.4’s PSNativeCommandUseErrorActionPreference ignores by default. Even PowerShell’s own tooling had this class of bug: the .NET global tool wrapper failed to propagate the native return code until PR #10461 fixed it.

Workaround

Section titled “Workaround”
  • After every native command that matters: if ($LASTEXITCODE -ne 0) { throw ... }.
  • PowerShell 7.4+: set $PSNativeCommandUseErrorActionPreference = $true.
  • In CI steps, prefer explicit exit-code checks over trusting the step to fail.

Refs

Section titled “Refs”