Update-DbaInstance not working

[dieterQBIT]

Verified issue does not already exist?

No, I did not search

What error did you receive?

First I installed the package through Install-Module dbatools and accepted all terms.
Next I want to try Update-DbaInstance but it keeps crashing every time.

`Update-DbaInstance
WARNING: [14:10:42][Update-DbaInstance] LT-DIETER is pending a reboot. Reboot the computer before proceeding.
Cannot index into a null array.
At line:95234 char:9

•     $mainPathIsNetwork = $Path[0] | Test-NetworkPath
  

•     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  

  • CategoryInfo : InvalidOperation: (:) [], RuntimeException
  • FullyQualifiedErrorId : NullArray`

I don't know why it keeps saying pending reboot because I just restarted, didn't help.

I'm on a laptop with up-to-date Windows 11 en SQL Server 2025 Enterprise Developer Edition (Microsoft SQL Server 2025 (RTM-GDR) (KB5077468) - 17.0.1105.2 (X64) Feb 13 2026 16:56:09 Copyright (C) 2025 Microsoft Corporation Enterprise Developer Edition (64-bit) on Windows 10 Pro 10.0 (Build 26200: ) (Hypervisor) )

I would expect it to download CU3 (17.0.4025.3) but nothing is working. I'm running the Powershell in admin-mode

Afterwards I also tried
Update-DbaInstance -Download

but that gives exact the same error.

I even tried
Update-DbaInstance -Download -Path D:\zandbak

I doesn't give an error, but doesn't do anything else.

Let me know if you need extra information.

Steps to Reproduce

# provide your command(s) executed pertaining to dbatools
# please include variable values (redacted or fake if needed) for reference

Please confirm that you are running the most recent version of dbatools

I do - download it today.

Other details or mentions

No response

What PowerShell host was used when producing this error

Windows PowerShell (powershell.exe)

PowerShell Host Version

5.1.26100.7920

SQL Server Edition and Build number

Microsoft SQL Server 2025 (RTM-GDR) (KB5077468) - 17.0.1105.2 (X64) Feb 13 2026 16:56:09 Copyright (C) 2025 Microsoft Corporation Enterprise Developer Edition (64-bit) on Windows 10 Pro 10.0 (Build 26200: ) (Hypervisor)

.NET Framework Version

PSChildName Version Release

---

v2.0.50727 2.0.50727.4927
v3.0 3.0.30729.4926
Windows Communication Foundation 3.0.4506.4926
Windows Presentation Foundation 3.0.6920.4902
v3.5 3.5.30729.4926
Client 4.8.09221 533509
Full 4.8.09221 533509
Client 4.0.0.0

[andreasjordan]

@claude can you please show what registry keys we use to test for a pending reboot?

[claude]

Claude finished @andreasjordan's task in 23s —— View job

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Registry Keys Used for Pending Reboot Detection

The function Test-PendingReboot (in private/functions/Test-PendingReboot.ps1) checks three registry locations in order:

1. Component Based Servicing (Vista/2008+)

HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Component Based Servicing
Value: RebootPending

2. Windows Update Auto Update (WUAU)

HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\WindowsUpdate\Auto Update
Value: RebootRequired

3. Pending File Rename Operations

HKLM:\SYSTEM\CurrentControlSet\Control\Session Manager
Value: PendingFileRenameOperations

If any of these values exist (not necessarily set to $true — just present in the registry), the function returns $true and triggers the "pending reboot" warning.

This is likely the root cause of the issue reporter's problem: one of these registry values exists on their machine even after a reboot (e.g., a leftover PendingFileRenameOperations entry), causing the false positive. The -NoPendingRename switch can be passed to skip the third check, but it's not currently exposed as a user-facing parameter in Update-DbaInstance.

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[andreasjordan]

@dieterQBIT please have a look at these registry keys. Removing them will solve your issue.

[dieterQBIT]

I'll take a look asap!

[dieterQBIT]

Ok, I found

HKLM:\SYSTEM\CurrentControlSet\Control\Session Manager
Value: PendingFileRenameOperations

on my server.

But that was just a sidenote. I keep getting the "Cannot index into a null array", even on my own laptop where the pendig reboot-message is now gone.

[andreasjordan]

You need to use the parameter -Path wich needs to point to the folder containing the patches.

[dieterQBIT]

According https://dbatools.io/Update-DbaInstance/ -Path is optional. Whats the point of having a script checking for updates if I have to point to a folder already containing the updates, which I have to download manually first?

[andreasjordan]

Please read the documentation and the examples. Example 8 uses the -Download parameter but still needs a path to store the downloaded file. You are right that -Path is not mandatory by parameter definition and there is not test for it beeing empty.

@claude please have a look at this issue. We need to test if $Path is empty early in the code. Please provide a pull request for that.

[claude]

Claude finished @andreasjordan's task in 1m 54s —— View job • claude/issue-10266-20260323-1343 • Create PR ➔

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Tasks

• Gather context and understand the request
• Find Update-DbaInstance source code
• Identify where $Path validation should be added
• Implement the fix
• Commit and push changes

Summary

The root cause was that $Path defaults to (Get-DbatoolsConfigValue -Name 'Path.SQLServerUpdates'), which returns $null when no default is configured. This caused a crash at line 617 ($mainPathIsNetwork = $Path[0] | Test-NetworkPath) with the unhelpful "Cannot index into a null array" error.

Fix: Added an early validation check in the begin block (after parameter validation), which stops execution with a clear, actionable error message when $Path is empty:

Path is required. Please provide a -Path to a folder containing (or to store)
SQL Server updates, or configure a default with
Set-DbatoolsConfig -Name Path.SQLServerUpdates -Value 'C:\patches'.

This applies whether the user runs Update-DbaInstance, Update-DbaInstance -Download, or any other variant without a path configured.

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