Can I get detailed exception stacktrace in PowerShell?

Question

Runing such script:

 1: function foo()
 2: {
 3:    bar
 4: }
 5: 
 6: function bar()
 7: {
 8:     throw \"test\"
 9: }
10: 
11: foo

I see

Answer 1

There are cases where PowerShell doesn't seem to keep a backtrace, like calling a method or calling a function with .Invoke(). For that, Set-PSDebug -Trace 2 may come in handy. It will print every executed line of the running script.

Try flipping # on (1) and (2) and running WrapStackTraceLog({ function f{ 1/0 } ; & f }) # let's divide by zero

Function WrapStackTraceLog($func) {
    try {
        # return $func.Invoke($args)  # (1)
        return (& $func $args)  # (2)
    } catch {
        Write-Host ('=' * 70)
        Write-Host $_.Exception.Message
        Write-Host ('-' * 70)
        Write-Host $_.ScriptStackTrace
        Write-Host ('-' * 70)
        Write-Host "$StackTrace"
        Write-Host ('=' * 70)
    }
}

Branch (1) exception caught:

Exception calling "Invoke" with "1" argument(s): "Attempted to divide by zero."

Branch (2) is more informative:

at f, <No file>: line 1
at <ScriptBlock>, <No file>: line 1
at global:WrapStackTraceLog, <No file>: line 4
at <ScriptBlock>, <No file>: line 1

But, you can still trace your Invokes with tracing on, branch (1):

DEBUG:     ! CALL function 'f'
DEBUG:    1+ WrapStackTraceLog({ function f{  >>>> 1/0 } ; & f })
DEBUG:    6+          >>>> Write-Host ('=' * 70)
======================================================================
DEBUG:    7+          >>>> Write-Host $_.Exception.Message
Exception calling "Invoke" with "1" argument(s): "Attempted to divide by zero."

Answer 2

You can not get a stack trace from exceptions of the PowerShell code of scripts, only from .NET objects. To do that, you will need to get the Exception object like one of these:

$Error[0].Exception.StackTrace
$Error[0].Exception.InnerException.StackTrace
$Error[0].StackTrace

Answer 3

Powershell 3.0 adds a ScriptStackTrace property to the ErrorRecord object. I use this function for error reporting:

function Write-Callstack([System.Management.Automation.ErrorRecord]$ErrorRecord=$null, [int]$Skip=1)
{
    Write-Host # blank line
    if ($ErrorRecord)
    {
        Write-Host -ForegroundColor Red "$ErrorRecord $($ErrorRecord.InvocationInfo.PositionMessage)"

        if ($ErrorRecord.Exception)
        {
            Write-Host -ForegroundColor Red $ErrorRecord.Exception
        }

        if ((Get-Member -InputObject $ErrorRecord -Name ScriptStackTrace) -ne $null)
        {
            #PS 3.0 has a stack trace on the ErrorRecord; if we have it, use it & skip the manual stack trace below
            Write-Host -ForegroundColor Red $ErrorRecord.ScriptStackTrace
            return
        }
    }

    Get-PSCallStack | Select -Skip $Skip | % {
        Write-Host -ForegroundColor Yellow -NoNewLine "! "
        Write-Host -ForegroundColor Red $_.Command $_.Location $(if ($_.Arguments.Length -le 80) { $_.Arguments })
    }
}

The Skip parameter lets me leave Write-Callstack or any number of error-handling stack frames out of the Get-PSCallstack listing.

Note that if called from a catch block, Get-PSCallstack will miss any frames between the throw site and the catch block. Hence I prefer the PS 3.0 method even though we have fewer details per frame.

Answer 4

There is the automatic variable $StackTrace but it seems to be a little more specific to internal PS details than actually caring about your script, so that won't be of much help.

There is also Get-PSCallStack but that's gone as soon as you hit the exception, unfortunately. You could, however, put a Get-PSCallStack before every throw in your script. That way you get a stack trace immediately before hitting an exception.

I think one could script such functionality by using the debugging and tracing features of Powershell but I doubt it'd be easy.

Answer 5

Maybe I've misunderstood something, but my issue here is that I've not been seeing powershell script stack traces for inner exceptions.

In the end I ended up searching $Global:Error for an exception's Error Eecord object to retrieve the script stack trace.

<#
.SYNOPSIS
   Expands all inner exceptions and provides Script Stack Traces where available by mapping Exceptions to ErrorRecords

.NOTES
   Aggregate exceptions aren't full supported, and their child exceptions won't be traversed like regular inner exceptions
   
#>
function Get-InnerErrors ([Parameter(ValueFrompipeline)] $ErrorObject=$Global:Error[0])
{
   # Get the first exception object from the input error
   $ex = $null
   if( $ErrorObject -is [System.Management.Automation.ErrorRecord] ){
       $ex = $ErrorObject.Exception 
   }
   elseif( $ErrorObject -is [System.Exception] ){
       $ex = $ErrorObject
   } 
   else
   {
       throw "Unexpected error type for Get-InnerErrors: $($ErrorObject.GetType()):`n $ErrorObject"
   }

   Write-Debug "Walking inner exceptions from exception"
   for ($i = 0; $ex; $i++, ($ex = $ex.InnerException))
   {  
       $ErrorRecord = $null

       if( $ex -is [System.Management.Automation.IContainsErrorRecord] ){ 

           Write-Debug "Inner Exception $i : Skipping search for ErrorRecord in `$Global:Error, exception type implements IContainsErrorRecord" 
           $ErrorRecord = ([System.Management.Automation.IContainsErrorRecord]$ex).ErrorRecord
       }
       else {

           # Find ErrorRecord for exception by mapping exception to ErrorRecrods in $Global:Error

           ForEach( $err in $Global:Error ){# Need to use Global scope when referring from a module
               if( $err -is [System.Management.Automation.ErrorRecord] ){
                  if( $err.Exception -eq $ex ){
                       $ErrorRecord = $err 
                       Write-Debug "Inner Exception $i : Found ErrorRecord in `$Global:Error" 
                       break
                   }
               } 
               elseif( $err -is [System.Management.Automation.IContainsErrorRecord] ) {
                   if( $err -eq $ex -or $err.ErrorRecord.Exception -eq $ex ){
                       $ErrorRecord = $err.ErrorRecord
                       Write-Debug "Inner Exception $i : Found ErrorRecord in `$Global:Error" 
                       break
                   }
               } 
               else {
                   Write-Warning "Unexpected type in `$Global:Error[]. Expected `$Global:Error to always be an ErrorRecrod OR exception implementing IContainsErrorRecord but found type: $($err.GetType())"
               }
           }
       }

       if( -not($ErrorRecord) ){
           Write-Debug "Inner Exception $i : No ErrorRecord could be found for exception of type: $($ex.GetType())" 
       }
       
      
       # Return details as custom object

       [PSCustomObject] @{
           ExceptionDepth      = $i
           Message             = $ex.Message
           ScriptStackTrace    = $ErrorRecord.ScriptStackTrace  # Note ErrorRecord will be null if exception was not from Powershell
           ExceptionType       = $ex.GetType().FullName
           ExceptionStackTrace = $ex.StackTrace
       }
   }
}

Example Usage:

function Test-SqlConnection
{
    $ConnectionString = "ThisConnectionStringWillFail"
    try{
        $sqlConnection = New-Object System.Data.SqlClient.SqlConnection $ConnectionString;
        $sqlConnection.Open();
    }
    catch
    {
        throw [System.Exception]::new("Sql connection failed with connection string: '$ConnectionString'", $_.Exception)
    }
    finally
    {
        if($sqlConnection){
            $sqlConnection.Close();
        }
    }
}


try{
    Test-SqlConnection
}
catch {
    Get-InnerErrors $_
}

Example output:

ExceptionDepth      : 0
Message             : Sql connection failed with connection string: 'ThisConnectionStringWillFail'
ScriptStackTrace    : at Test-SqlConnection, <No file>: line 11
                      at <ScriptBlock>, <No file>: line 23
ExceptionType       : System.Exception
ExceptionStackTrace : 

ExceptionDepth      : 1
Message             : Exception calling ".ctor" with "1" argument(s): "Format of the initialization string does not conform to specification starting at index 0."
ScriptStackTrace    : 
ExceptionType       : System.Management.Automation.MethodInvocationException
ExceptionStackTrace :    at System.Management.Automation.DotNetAdapter.AuxiliaryConstructorInvoke(MethodInformation methodInformation, Object[] arguments, Object[] originalArguments)
                         at System.Management.Automation.DotNetAdapter.ConstructorInvokeDotNet(Type type, ConstructorInfo[] constructors, Object[] arguments)
                         at Microsoft.PowerShell.Commands.NewObjectCommand.CallConstructor(Type type, ConstructorInfo[] constructors, Object[] args)

ExceptionDepth      : 2
Message             : Format of the initialization string does not conform to specification starting at index 0.
ScriptStackTrace    : 
ExceptionType       : System.ArgumentException
ExceptionStackTrace :    at System.Data.Common.DbConnectionOptions.GetKeyValuePair(String connectionString, Int32 currentPosition, StringBuilder buffer, Boolean useOdbcRules, String& keyname, String& 
                      keyvalue)
                         at System.Data.Common.DbConnectionOptions.ParseInternal(Hashtable parsetable, String connectionString, Boolean buildChain, Hashtable synonyms, Boolean firstKey)
                         at System.Data.Common.DbConnectionOptions..ctor(String connectionString, Hashtable synonyms, Boolean useOdbcRules)
                         at System.Data.SqlClient.SqlConnectionString..ctor(String connectionString)
                         at System.Data.SqlClient.SqlConnectionFactory.CreateConnectionOptions(String connectionString, DbConnectionOptions previous)
                         at System.Data.ProviderBase.DbConnectionFactory.GetConnectionPoolGroup(DbConnectionPoolKey key, DbConnectionPoolGroupOptions poolOptions, DbConnectionOptions& userConnectionOptions)
                         at System.Data.SqlClient.SqlConnection.ConnectionString_Set(DbConnectionPoolKey key)
                         at System.Data.SqlClient.SqlConnection.set_ConnectionString(String value)
                         at System.Data.SqlClient.SqlConnection..ctor(String connectionString, SqlCredential credential)

Answer 6

Here's a way: Tracing the script stack

The core of it is this code:

    1..100 | %{ $inv = &{ gv -sc $_ myinvocation }