Continue execution on Exception

Question

Below is the script I want to execute. The issue here is once an exception occurs it stops executing, I used continue in the catch block but that did not work. How do I get it working even after an exception occurs it should loop in foreach.

I also used a while($true) loop but that went into infinite loop. How to go about it?

$ErrorActionPreference = "Stop";
try 
{
# Loop through each of the users in the site
foreach($user in $users)
{
    # Create an array that will be used to split the user name from the domain/membership provider
    $a=@()


    $displayname = $user.DisplayName
    $userlogin = $user.UserLogin


    # Separate the user name from the domain/membership provider
    if($userlogin.Contains('\'))
    {
        $a = $userlogin.split("\")
        $username = $a[1]
    }
    elseif($userlogin.Contains(':'))
    {
        $a = $userlogin.split(":")
        $username = $a[1]
    }

    # Create the new username based on the given input
    $newalias = $newprovider + "\" + $username

    if (-not $convert)
    {
        $answer = Read-Host "Your first user will be changed from $userlogin to $newalias. Would you like to continue processing all users? [Y]es, [N]o"

        switch ($answer)
        {
            "Y" {$convert = $true}
            "y" {$convert = $true}
            default {exit}
        }
    }   

    if(($userlogin -like "$oldprovider*") -and $convert)
    {  

        LogWrite ("Migrating User old : " + $user + " New user : " + $newalias + "    ")
        move-spuser -identity $user -newalias $newalias -ignoresid -Confirm:$false
        LogWrite ("Done")
    }   
} 
}
catch  {
    LogWrite ("Caught the exception")
    LogWrite ($Error[0].Exception)
} 

Vociferant

Why not change $ErrorActionPreference = "Continue" ? Doesn't work for you? – Wunder

Is there a specific line that's causing the exception? – Optimum

Answer 1

You use try {...} catch {...} when you want to handle errors. If you want to ignore them, you should set $ErrorActionPreference = "Continue" (or "SilentlyContinue") as @C.B. suggested, or use -ErrorAction "SilentlyContinue" for the particular operation raising the error. If you want to handle errors from a certain instruction, you'd put that instruction in the try {...} catch {...} block, not the entire loop, e.g.:

foreach($user in $users) {
  ...
  try {
    if(($userlogin -like "$oldprovider*") -and $convert) {  
      LogWrite ("Migrating User old : " + $user + " New user : " + $newalias + "    ")
      move-spuser -identity $user -newalias $newalias -ignoresid -Confirm:$false
      LogWrite ("Done")
    }   
  } catch {
    LogWrite ("Caught the exception")
    LogWrite ($Error[0].Exception)
  }
} 

Penetration

Since i wanted to log non terminating errors, setting '$ErrorActionPreference' did not help me much. Only time it worked is '$ErrorActionPreference = "Stop"' but than the execution halts on catch. I wanted to continue exection even on error. Please see my answer, that solved my issue. Thanks for your answer. :) – Vociferant

You need Stop as the error action for try..catch to work, because it only catches terminating errors. Without a terminating error there'd be nothing to catch in the first place. – Penetration

-ErrorAction doesn't work for exceptions. E.g. if you want to ignore failure of Set-ExecutionPolicy, the only way to get no error output is to Catch[System...] { }. Note you need the space, otherwise Catch is parsed to nothing and that causes an error! – Karakorum

Answer 2

You seem to have placed the "catch" outside the loop body, so that aborts the loop. Put the catch inside the loop

Avernus

Please some more explanation and code, as these might help for future reference – Peon

In the OP code, the catch block sits outside the loop. Here is an example: foreach($a in $list) { try { dosomething } Write-Output "Yay, I did something!" } Catch { Write-output "Uh-oh. Armageddon." } When the exception is caught, it is caught outside the loop. – Avernus

Answer 3

Modified the code as below. Used the following piece of code after move-spuser -identity $user -newalias $newalias -ignoresid -Confirm:$false

if($?)
{
  LogWrite ("Done!")
  LogWrite ("  ")
}
else
{
  LogWrite ($Error[0].ToString())
  LogWrite ("  ")
}

Vociferant

Don't use $?. Ever. Instead check $LastExitCode (see here). – Penetration

Isn't $LastExitCode for executables, not for PowerShell cmdlets, scripts, or functions? – Dail

Answer 4

Something that worked for me is to set the $ErrorActionPreference variable to stop, and then reset it back to continue in the catch block:

$e = $ErrorActionPreference
$ErrorActionPreference="stop"

try
{
     #Do Something that throws the exception
}
catch
{
    $ErrorActionPreference=$e

}

$ErrorActionPreference=$e;

Tuttifrutti