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Diagnose skipped catch paths and native status

Classify terminating errors, non-terminating errors, native exit codes, preferences, partial output, and the script’s actual completion contract.

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Recognize the symptoms

A command writes an error but catch does not run, a native tool exits nonzero without the expected exception, or a script prints a success message after partial failure. The same source can behave differently across preference settings or editions. Preserve the command category, exact error, original result, and active version before adding a broad catch or disabling diagnostics.

Understand the likely causes

  • try/catch handles terminating errors, while applicable non-terminating errors can require a deliberate ErrorAction policy. Native stdout/stderr and exit codes have another contract, with newer preference behavior absent from 5.1. A later command can also obscure the original status, and a catch can hide failure by returning empty data as though it were a valid result.

1. Identify which execution and error system applies

Distinguish a PowerShell cmdlet/function from a native executable and record the actual resolved command. Preserve whether the operation produced partial success objects before reporting an error. Inspect supported ErrorAction parameters and preference scope without dumping secret-bearing state. Do not assume every stderr line is a PowerShell exception or every visible red message terminates execution. Compare the same invocation context and edition as the failing case. An isolated replacement should model the relevant failure category rather than accidentally removing the behavior being diagnosed.

2. Make the intended terminating boundary explicit

For a supported cmdlet, -ErrorAction Stop can route an applicable non-terminating error into a terminating path that try/catch can handle. Scope preference changes and restore reusable state when appropriate. Catch the intended exception or boundary error and preserve useful ErrorRecord context rather than replacing every failure with success. finally handles cleanup under language rules, not rollback of an external commit. The illustration below generates only a synthetic PowerShell error and remains non-runnable because the engine is unavailable; it is not a test against a file, service, or configured resource.

powershell Non-runnable ErrorAction boundary illustration 
try {
    Write-Error 'Synthetic controlled error' -ErrorAction Stop
}
catch {
    'handled terminating boundary'
}

The intended catch path follows documented Stop behavior for this cmdlet. No PowerShell error or catch execution was performed locally.

3. Interpret native exit status separately

Read the native tool’s documented success and expected-absence codes. Capture the relevant exit code before later native work changes it, and distinguish it from $? and stream content. PowerShell’s native-command preference and argument-passing behavior are version-dependent, so do not copy a 7-specific assumption into Windows PowerShell 5.1. A nonzero code may be expected for one tool and a required failure for another. A zero code can also coexist with invalid application output. Verify status and the public result independently without invoking a real administrative executable for diagnosis.

4. Keep recovery and final reporting truthful

Define whether partial output is discarded, retained with a failure envelope, or accepted under a documented partial-result contract. Do not let a successful logger or catch message become the only completion signal. Retry only under the operation’s safe-repeat policy, preserving uncertainty if a response was lost after effects. The offline decision model below separates an allowed absence from a required failure; it does not implement PowerShell exception promotion or native invocation. No provider, process, credential, remote connection, or service is accessed by the guide.

python Check a declared result-code policy offline 
results = [('required-transform', 7, {0}), ('optional-search', 1, {0, 1})]
for name, code, acceptable in results:
    print(name + ':' + ('accepted' if code in acceptable else 'failed'))
Expected output
required-transform:failed
optional-search:accepted

The allowed sets are synthetic application policy, not universal native exit meanings. The model executes no failing tool or PowerShell command.

Verify the fix

In a later authorized engine test, assert the original error category, catch behavior, preserved status, all emitted objects, cleanup outcome, and the caller’s final failure signal. Cover both partial output and expected absence. For this course, report only the offline model result and leave PowerShell/native runtime behavior untested.

Keep it from recurring

  • Document cmdlet and native failure contracts, scope preferences, keep diagnostic and data channels distinct, and test supported editions explicitly. Retain regressions for non-terminating errors, expected nonzero codes, and a later successful message that must not hide the original failure. Avoid catch-all empty results as an automatic repair.

Official references