Powershell error handling

Question

Take the below example.

Function Test-Function {
    try {
        [int]$var.ToString()
    }catch{
        Write-Error "Error inside Function"     
    }
}


try {
    Test-Function
}catch{
    Write-Error "Error inside try/catch of script"
}

Test-Function itself is generating an error (on purpose in this case, to test this behaviour), therefore hitting it's own catch. However, the Function call itself within the script, is also wrapped in a Try Catch statement, but the script only ever displays the catch of the function. Is this behaviour by design?

In .Net C# I've seen this many times and it's ok. When Test-Function catches an exception, error message it's more specific and that's the reason for nesting try/catch blocks. I personally don't do that but I re-throw the exception inside Test-Function catch block with new more descriptive error message so I only have to call my Logger once in the parent at the bottom of call stack. Here there's no Logger object, just a Write-Error, so it's ok. However I still prefer my method, as it aborts all execution at first error. Whereas the code you posted allows inconsistent code to keep running — Daniel Manta
– Daniel Manta, Commented Nov 23, 2017 at 18:56
I'm not sure I follow. Why doesn't the try catch calling the function catch an error? — PnP
– PnP, Commented Nov 23, 2017 at 18:58

Matt · Accepted Answer · 2017-11-23 20:55:58Z

4

The answer is how try-catch works and what Write-Error does. From Doc.Microsoft we know that....

The Write-Error cmdlet declares a non-terminating error

And looking at About_Try_Catch_Finally we see that it...

Describes how to use the Try, Catch, and Finally blocks to handle terminating errors.

^{Emphasis mine in both quotes}

Try catch is not going to capture the output from Write-Error and that is by design. If you want to pass a terminating error use throw

Function Test-Function {
    try {
        [int]$var1.ToString()
    }catch{
        throw "Error inside Function"     
    }
}

edited Nov 23, 2017 at 20:55

answered Nov 23, 2017 at 19:22

Matt

47k9 gold badges90 silver badges125 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Powershell error handling

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related