Demystifying Error Handling

Any error in PowerShell code surfaces as an error record object. Check out the function below which extracts all relevant error information from such error record:

function Get-ErrorInfo
{
  param
  (
    [Parameter(ValueFrompipeline)]
    [Management.Automation.ErrorRecord]$errorRecord
  )


  process
  {
    $info = [PSCustomObject]@{
      Exception = $errorRecord.Exception.Message
      Reason    = $errorRecord.CategoryInfo.Reason
      Target    = $errorRecord.CategoryInfo.TargetName
      Script    = $errorRecord.InvocationInfo.ScriptName
      Line      = $errorRecord.InvocationInfo.ScriptLineNumber
      Column    = $errorRecord.InvocationInfo.OffsetInLine
      Date      = Get-Date
      User      = $env:username
    }
    
    $info
  }
}

This function makes error handling code a lot shorter and easier to understand. If you must respond immediately to an error, use the try/catch concept, and make sure you instruct cmdlets via -ErrorAction Stop to immediately stop when an error occurs:

try
{
    Stop-Service -Name someservice -ErrorAction Stop
}  
catch 
{
    $_ | Get-ErrorInfo
}

If you want the code to complete, and only later check for errors that may have occurred, use -ErrorAction SilentlyContinue in conjunction with -ErrorVariable. Again, the function Get-ErrorInfo helps a lot:

$result = Get-ChildItem -Path C:\Windows -Filter *.ps1 -Recurse -ErrorAction SilentlyContinue -ErrorVariable myErrors
$myErrors | Get-ErrorInfo

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