Question

This self-answered question, written as of PowerShell (Core) v7.3.x, aims to address the following symptoms:

Sometimes, neither using -ErrorAction -Stop nor $ErrorActionPreference = Stop appears to be effective for being able to catch and handle an error via a try / catch statement.

以下是两个例子:

<编码> Get-NetAdapter 忽视<代码> 参考 = 封面或功能(从>,,但global<>>>>:

# Run on Windows. Affects both PowerShell editions. # The `catch` block isn t triggered, and the (still non-terminating) error prints. & { # Simulate running in a child scope. $ErrorActionPreference = Stop try { Get-NetAdapter nosuch } catch { "Should get here, but don t." } }

However, use of -ErrorAction Stop (Get-NetAdapter nosuch -ErrorAction Stop) does work as expected.

<编码> Get-AppLockerFile Information, in PowerShell (Core) v7+ only, 忽略了 both a non-global $ Action 参会:<0> 仅见以下表格:
# Run on Windows. Affects PowerShell (Core) v7+ only # The `catch` block isn t triggered, and the (still non-terminating) error prints. try { Get-AppLockerFileInformation NoSuch.exe -ErrorAction Stop } catch { "Should get here, but don t in PowerShell (Core)." }

因此,问题是:
何时确定<代码>-行动和/或 参考无效?
什么工作是没有的?

Answer 1

两个相关因素决定了<代码>-ErrorAction和/或$ 参考在发出特定指挥时无效:

从根本上说,由于强权壳牌复印件工程,在script模块(即,在PowerShell实施,而不是通过汇编的网络组装)上安装的指令,见p参引变量,包括<$_ErrActionorActionor。参考,但从全球范围,即not<>> 当你要求使用(非专用)文字或功能时。
这是非常不幸的,设计限制是。
common para <>em><<<a>a>。 ErrorActionP参比table,正如联系的Gite Hub期所讨论的那样,这意味着,如果某一文字模块的某一功能出现到another script model s function,后者将<>em>。 ErrorActionP参比。换言之: 除非丧失补偿职能,否则,-ErrorAction Stop归根结底是没有被保证为荣誉<>。

使用 .implicit remoting - which are by definition script <>>>>>>>>>>>>>>>>>> 复杂性:

由这些模块指挥的,甚至<代码>-ErrorAction Stop 无效,因为这一参数为propagated至remotelycut的指挥,而设计为remotely。正在发生的断层错误将 当地<>m> /em> 转化为无终止错误。

I believe the design rationale behind this to be the following, related to PowerShell remoting in general:

When targeting multiple remote machines, such as via Invoke-Command s -ComputerName parameter, a terminating error occurring remotely should not terminate the multi-machine operation overall, therefore such as remotely terminating errors are translated into locally non-terminating ones.

This logic applies to scenarios with implicit remoting too - despite the fact that by definition only one remote machine is being targeted.

虽然使用隐含的重温通常是要求采取明确行动,例如使用Import-PSSession。厘米度——有一种假设,即暗中转动automatically。缺省:

https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell. Ravi/about_PowerShell_Compatibility" rel=nofollow nore参赛人>>自动进口。

While this isn t technically remoting, given that everything happens on the local machine, the underlying cross-process communication mechanism is the same as in true remoting, which - as an aside - also reduces type fidelity - see this answer.

The only way to turn such remotely occurring, invariably non-terminating errors into terminating ones that can be caught with try / catch is to (temporarily) set the global incarnation of the $ErrorActionPreference variable to Stop , as shown below.

Workarounds:

For commands from regular script modules , i.e. modules implemented in PowerShell code that do not use implicit remoting, which includes CDXML-based modules):

而不是<代码> ErrorAction 缩略语:

try { Get-NetAdapter nosuch -ErrorAction Stop } catch { "OK, caught: $_" }

Caveats:

Unfortunately, these two mechanism aren t created equal: -ErrorAction Stop only acts on non-terminating errors, whereas $ErrorActionPreference = Stop acts on statement-terminating errors too - see this answer. However, in the context of using try / catch, this distinction doesn t matter, because a statement-terminating error by itself also triggers the catch block.

但是,如果目标功能的执行发生,则其他文字模块的指令<>不使用<代码>-ErrorAction,则<>自动生效>。 <>斯特罗内> 参考全球确保可预见的行为——见下点。

For commands from modules that use implicit remoting, which includes those loaded via the Windows PowerShell Compatibility feature (and which are by definition also script modules):

<>strong>(当时)将global$ErrorAction> 缩略语改为<条码>
& { # Simulate running in a child scope. $prevGlobalPref = $global:ErrorActionPreference $global:ErrorActionPreference = Stop try { Get-AppLockerFileInformation NoSuch.exe } catch { "OK, now we get here: $_" } finally { $global:ErrorActionPreference = $prevGlobalPref } }
As for how to tell whether a given command is from either module type: The following helper function, Get-CommandModuleType, tells you what type of module a given command is from, with output Script indicating a regular (non-implicitly-remoting) script module, and ImplicitRemoting an implicitly remoting one; see the comment-based help in the source code for details. Sample calls, from PowerShell (Core) on Windows: # -> Script Get-CommandModuleType.ps1 Get-NetAdapter # -> ImplicitRemoting Get-CommandModuleType.ps1 Get-AppLockerFileInformation function Get-CommandModuleType { <# .SYNOPSIS Indicates the type of module that the specified command is from. .DESCRIPTION Aliases are automatically resolved to their underlying commands. Note: * If the command *isn t from a module*, there is no output. * The output is a *string* that is one of the following: * ImplicitRemoting for an implicitly remoting module. * Script for regular script modules (that don t use implicit remoting) * Otherwise, the stringified version of the System.Management.Automation.ModuleType value reported by the `.ModuleType` property of the underlying module. * IMPORTANT: * Not all script modules report themselves as such via the underlying module s manifest; some of them report just Manifest . If you want to see this formal value, use the -Raw switch. .EXAMPLE Get-CommandModuleType Get-NetAdapter Reports the *de facto* type of module that hosts the Get-NetAdapter command. .EXAMPLE Get-CommandModuleType Get-NetAdapter -Raw Reports the *formal* type of module that hosts the Get-NetAdapter, as implied by its manifest. #> [CmdletBinding()] param( [Parameter(Mandatory)] [string] $CommandName, [switch] $Raw ) $command = Get-Command $CommandName if ($command -and $command.ResolvedCommand) { $command = $command.ResolvedCommand Write-Verbose "Resolved command is: $command" } if ($module = $command.Module) { Write-Verbose "Source module is: $module" if (-not $Raw -and $command.CommandType -eq Function -and $module) { # a script module if ($module.PrivateData.ImplicitRemoting) { # an implicitly remoting module ImplicitRemoting } else { Script } } else { if ($Raw) { Write-Verbose Reporting raw module type, i.e as manifested. } $module.ModuleType.ToString() } } }

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