Cannot index into a null array on assignment?

Question

all.

About to lose it - This was working hours ago.

So when I run this I get

Cannot index into a null array.
At line:3 char:15
+ $backlog[0]=$(Get-DFSRBacklog -sourcecomputername:ts-fileshares2 -destinationcom ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidOperation: (:) [], RuntimeException
    + FullyQualifiedErrorId : NullArray

Issue being, when I search here and elsewhere, I find people making issues assigning a null array TO a variable. Not assigning to the array.

Below is most of the code (I am running this against multiple fileshares, too lazy to change server names in six lines. Typically backlog[] contains 6 sets of replies.

clear-host
$backlog[0]=$(Get-DFSRBacklog -sourcecomputername:a -destinationcomputername:b -Verbose) 4>&1

#$collection is one array result. This will be easier to split out into by-server later.
[int]$total = 0
foreach ($collection in $backlog)
{
    $collection | ForEach-Object -Process {
        if ($_.getType().FullName.equals("System.Management.Automation.VerboseRecord"))
        {
            #$_ | Get-Member
            #Write-Host $_.Message
            if ($_.Message -like "*has a backlog*")
            {
                #testing write-host $_.Message.split(" ")[12]
                $total += [convert]::ToInt32($_.Message.split(" ")[12],10)
            }
        }
    }
}
#testing Write-Host $total
[Environment]::SetEnvironmentVariable("TOTALFILESHAREBACKLOG",$total, "Machine")
#testing Write-Host $env:TOTALFILESHAREBACKLOG

As I said, this was working hours ago. Not sure if I have some weird variable stuck, but this is on out prod server (no way to get DFSR backlog from a non-prod server) so I don't want to reboot the entire server.

This is a signed powershell script that is running on a schedule (zabbix pulls the env variable later for reporting) but that shouldn't affect it. The only thing that I changed between this working and not working was moving where this file was saved.

The Powershell Get-DFSRBacklog does always return a value or print an error, so that's not it.

Even doing $backlog[0] = 1 throws an error.

P.P.S.

Name                           Value                                                                                 
----                           -----                                                                                 
PSVersion                      4.0                                                                                   
WSManStackVersion              3.0                                                                                   
SerializationVersion           1.1.0.1                                                                               
CLRVersion                     4.0.30319.42000                                                                       
BuildVersion                   6.3.9600.17400                                                                        
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0}                                                                  
PSRemotingProtocolVersion      2.2

"Typically backlog[] contains 6 sets of replies." - and yet in this case, it is $null. So where is $backlog being defined? — TessellatingHeckler
– TessellatingHeckler, Commented Oct 11, 2017 at 18:42
It is defined as it is created and assigned, no? This is the entirety of the script (aside from having five other sets of responses put into backlog) — Monica Apologists Get Out
– Monica Apologists Get Out, Commented Oct 11, 2017 at 18:43
If that is the entire script then I'm going with "it never worked" because $x[0] = 1 hasn't ever been a valid way to define a variable from scratch. It would have to be $backlog=$(Get-DFSRBacklog -sourcecomputername:a -destinationcomputername:b -Verbose) 4>&1 with no [] for the first definition. Once it is an array, then you can [0] it. — TessellatingHeckler
– TessellatingHeckler, Commented Oct 11, 2017 at 18:43
I think I'm having a mandela moment, then. Perhaps it didn't work but I swear it did. I even have records in my Zabbix box from it updating the variable. Perhaps I had $backlog created from a previous incarnation (I wrote all of this in one sitting) and it still was initialized. At any rate, just after I posted this I tried adding $backlog=0,0,0,0,0,0 at the top and it resolved the issue. I'll post it as an answer once I test. I could have sworn you didn't have to initialize an array before using it in Powershell. — Monica Apologists Get Out
– Monica Apologists Get Out, Commented Oct 11, 2017 at 18:46
Do you want an array of backlogs or just 1 backlog that contains an array of items? — zdan
– zdan, Commented Oct 11, 2017 at 18:51

Monica Apologists Get Out · Accepted Answer · 2017-10-11 18:58:18Z

1

Answer: I am a dumbass.

You need to initialize variables before you can treat them as an array, even for assignment. The fix was to add $backlog=0,0,0,0,0,0 at the top of the $backlog[x] assignments.

answered Oct 11, 2017 at 18:58

Monica Apologists Get Out

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