Error Handling method call on a null-valued expression

Question

I am getting the following non-terminating error in PowerShell. I want to catch this and write-host a generic statement, rather than see the error.

Here is the output:

You cannot call a method on a null-valued expression. At C:\PowerShell Scripts\windowsUpdates.ps1:17 char:2 + $a = $key.GetValue("LastSuccessTime") + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + CategoryInfo : InvalidOperation: (:) [], ParentContainsErrorRec ordException + FullyQualifiedErrorId : InvokeMethodOnNull

My catch statement is currently not "catching" this.

Any help is appreciated.

Answer 1

I figured this out. I simply added if($variable -eq $null){write-host "message";}.

Answer 2

There are a few options

Depending on where you are getting the null variable from you could add

-ErrorAction Stop" after the command so that it treats the non-terminating error as a terminating error.

If that's not an option you could throw an error to force your catch statement to catch the error

if($variable -eq $null){Throw("Variable is Null")}

Or you can make it so that all errors are treated as terminating errors so your catch statement will catch anything that is thrown

$ErrorActionPreference = "Stop"

For more information look at the MSDN documentation here: http://blogs.msdn.com/b/kebab/archive/2013/06/09/an-introduction-to-error-handling-in-powershell.aspx