ConvertFrom-Json does not respect -ErrorAction

Steps to reproduce

Run the following expressions:

"some invalid JSON string" | ConvertFrom-Json -ErrorAction Ignore
"some invalid JSON string" | ConvertFrom-Json -ErrorAction SilentlyContinue

Expected behavior

Both expressions write no error to the console, and return either $null or the empty string.

Actual behavior

The expressions write an error to the console and throw the following exception:

ConvertFrom-Json : Invalid JSON primitive: some invalid JSON string.
At line:1 char:12
+ "some invalid JSON string" | ConvertFrom-Json -ErrorAction Ignore
+            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [ConvertFrom-Json], ArgumentException
    + FullyQualifiedErrorId : System.ArgumentException,Microsoft.PowerShell.Commands.ConvertFromJsonCommand

Environment data

> $PSVersionTable

Name                           Value
----                           -----
PSVersion                      5.1.14393.206
PSEdition                      Desktop
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0...}
BuildVersion                   10.0.14393.206
CLRVersion                     4.0.30319.42000
WSManStackVersion              3.0
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1

If this is not the appropriate place to report bugs against v5.x, please let me know where I can.

Alastair Smith (@alastairs)

Alastair Smith (@alastairs) Could you please test this with recent Powershell 6 build?

Ilya (@iSazonov)

Ilya (@iSazonov) The behaviour is the same with 6.0.0-alpha13

> $PSVersionTable

Name                           Value
----                           -----
PSEdition                      Core
PSVersion                      6.0.0-alpha
PSRemotingProtocolVersion      2.3
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0...}
WSManStackVersion              3.0
CLRVersion
GitCommitId                    v6.0.0-alpha.13
BuildVersion                   3.0.0.0
SerializationVersion           1.1.0.1

BTW, I love that trying this out was just a case of extracting a zip file somewhere and not a full-blow installer. Great work! 👍

Some further information in case it's useful: my $ErrorActionPreference variable is set to "Stop".

Hemant Mahawar (@HemantMahawar)

@PowerShell/powershell-committee (subset of Hemant Mahawar (@HemantMahawar) Jason Shirk (@lzybkr) Kenneth Hansen (@khansen00) and myself) agree that the original issue (#2860) is by design. It is unreasonable for ConvertFrom-Json to emit anything but an error when receiving malformed input, and terminating errors are not respected by -ErrorAction. If a developer absolutely wants to make a conscious choice to ignore that terminating error, they should use try/catch.

Okay, now I actually don't know what's going on. It would appear that this is currently a non-terminating error:

ConvertFrom-Json : Conversion from JSON failed with error: Unexpected character encountered while parsing value: s.
Path '', line 0, position 0.
At line:1 char:18
+ "some invalid" | ConvertFrom-Json -ErrorAction SilentlyContinue; 2+2
+                  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [ConvertFrom-Json], ArgumentException
    + FullyQualifiedErrorId : System.ArgumentException,Microsoft.PowerShell.Commands.ConvertFromJsonCommand

4

Note: the 2+2 still gets executed

If that's the case, then -ErrorAction should be respected, right?

Joey,
The proposed fix for this was not accepted and resolved as by-design. Under the hood, Json.Net throws an ArgumentException for malformed json content.

Then I'm not understanding why it's not terminating the statement above....my understanding of PS errors (which may be busted, but please help me understand):

terminating errors (usually surfaced from internal exceptions) should terminate the script block or statement. In this case, if the ArgumentException is terminating at the PS level, the 2+2 should then not be executed.
Non-terminating errors respect -ErrorAction. If ArgumentException was caught as a non-terminating error, -ErrorAction SilentlyContinue should silence the error.

What am I missing here?

This appears to be a side-effect of Cmdlet.ThrowTerminatingError; -ErrorAction is apparently ignored. It's not clear if it is intentional. I see the same behavior on Windows PowerShell.
Here's a couple of PS functions that illustrate the behavior difference:

function TerminatingError
{
    $exception = [System.ArgumentException]::new("argexception")
    $err = [System.Management.Automation.ErrorRecord]::new( `
        $exception,`
        'error',`
        [System.Management.Automation.ErrorCategory]::NotSpecified,`
        $null)
    $cmdlet = [Microsoft.PowerShell.Commands.GetDateCommand]::new()
    $cmdlet.ThrowTerminatingError($err)
}

function ExceptionError
{
    $exception = [System.ArgumentException]::new("argexception")
    throw $exception
}

Okay, now I really don't know what's going on. With your two functions, TerminatingError;2+2 shows that it's not really terminating, but ExceptionError;2+2 is terminating.

Dan Travison (@dantraMSFT)

Unless you have some more insight, Dan Travison (@dantraMSFT), I'll probably open another issue and figure out what the intended behavior is supposed to be.

Bruce Payette (@BrucePay)

cc Bruce Payette (@BrucePay)

Behavior with TerminatingError and Exception is inconsistent, not sure if intended.

Alright, I'm closing it, I'll follow up offline or in another issue.

For posterity, my understanding of terminating errors was wrong. A terminating error cancels execution of the current pipeline or expression, not of an entire script block.

A better way to check for terminating errors is to just use try/catch:

C:\Program Files\PowerShell\6.0.0-alpha.18> try {"fdasf" | convertfrom-json} catch {1}
1
C:\Program Files\PowerShell\6.0.0-alpha.18> try {ls foo} catch {1}
ls : Cannot find path 'C:\Program Files\PowerShell\6.0.0-alpha.18\foo' because it does not exist.
At line:1 char:6
+ try {ls foo} catch {1}
+      ~~~~~~
    + CategoryInfo          : ObjectNotFound: (C:\Program File....0-alpha.18\foo:String) [Get-ChildItem], ItemNotFound
   Exception
    + FullyQualifiedErrorId : PathNotFound,Microsoft.PowerShell.Commands.GetChildItemCommand

Joey Aiello (@joeyaiello)

Joey Aiello (@joeyaiello):

I had the same misconception, and I think the source is that the current help topics conflate statement-terminating errors with script-terminating errors - please see Our Error Handling, Ourselves - time to fully understand and properly document PowerShell's error handling.

I know this is an old closed issue... but using "resolvedByDesign" as an excuse is lame... The optics of this is taht an error is an error is an error, irrespective of terminating or non-terminating. Thus-ErrorAction should be respected for all errors and cmdlets, or it becomes inconsistent and unpredictable. End developers should be free to use errorAction as they see fit.

$json = ("apple" | convertFrom-json -ErrorAction SilentlyContinue)
if (!$json) { write-warning "Issue with json input - ignoring" }

OR maybe we need -TerminatingErrorAction as a new switch? 😊

I find ConvertFrom-Json not respecting -ErrorAction counterintuitive and a poor user experience.

I'm reading a stream of one-line json's, and try catch can't be embedded in a pipeline, so here is my workaround:
kubectl logs my-pod | ConvertFrom-JsonSafe

function ConvertFrom-JsonSafe {
    [CmdletBinding()]
    param (
        [Parameter(ValueFromPipeline, Mandatory=$true)]
        [string]$InputObject,
        [Switch]$Quiet
    )

    process {
        try {
            $InputObject | ConvertFrom-Json
        } catch {
            # If $Quiet is not set, log a warning
            if (-not $Quiet) {
                Write-Warning "Failed to convert JSON: $InputObject"
            }
        }
    }
}

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ConvertFrom-Json does not respect -ErrorAction #2860

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ConvertFrom-Json does not respect -ErrorAction #2860

Description

Steps to reproduce

Expected behavior

Actual behavior

Environment data

Activity

alastairs commented on Dec 8, 2016

iSazonov commented on Dec 8, 2016

alastairs commented on Dec 8, 2016

alastairs commented on Dec 8, 2016

joeyaiello commented on Feb 16, 2017

joeyaiello commented on Apr 13, 2017

dantraMSFT commented on Apr 13, 2017

joeyaiello commented on Apr 14, 2017

dantraMSFT commented on Apr 14, 2017

joeyaiello commented on Apr 14, 2017

joeyaiello commented on Apr 14, 2017

SteveL-MSFT commented on Apr 14, 2017

joeyaiello commented on Apr 17, 2017

joeyaiello commented on Apr 18, 2017

mklement0 commented on Aug 15, 2017

awsles commented on May 23, 2021

gerardog commented on Oct 10, 2024

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