PowerShell, SharePoint: Get-PnPSiteTemplate Error - powershell

Question

i am getting an error using PnP PowerShell cmdlet: Get-PnPSiteTemplate. I am a global admin and site collection admin as well.
Custom Scripts are enabled:
set-sposite https://tenant.sharepoint.com/sites/TestSite -denyaddandcustomizepages $false
Connect-PnPOnline -Url https://tenant.sharepoint.com/sites/TestSite -Interactive
Get-PnPSiteTemplate -Out "C:TempDemo.xml"
Get-PnPSiteTemplate : Attempted to perform an unauthorized operation.
At C:\Users\userX\Desktop\Script.ps1:3 char:1
+ Get-PnPSiteTemplate -Out "C:TempDemo.xml"
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : WriteError: (:) [Get-PnPSiteTemplate], ServerUnauthorizedAccessException
+ FullyQualifiedErrorId : EXCEPTION,PnP.PowerShell.Commands.Provisioning.Site.GetSiteTemplate
Anyone an idea? MS says PnP is open source, so no really support...
Goal is to copy a complete SharePoint list with all items and meta data to anothe site. Like this:
https://www.drware.com/copy-a-list-with-list-items-to-another-site/
Thanks! :)

Answer 1

I rechecked the command with latest version of PnP.PowerShell (version 1.7.0) on a clean communication site with a sample list with couple of items, nothing more, and works 🤔.
Could you also first retry on some test clean site with just one custom list and see if you have the same error? Maybe the problem you are having is connected to some customization you have on this site as the Get-PnPSiteTemplate without any parameters will export an template of the full site (including the list, but also all other stuff like some custom apps which maybe you don't have permission to do)
other thing you could try is to run the cmdlet to retrieve only the list you are interested in together with data:
# this will export the template only of the selected list
Get-PnPSiteTemplate -Out "C:\TempDemo.xml" -ListsToExtract "testList" -Handlers Lists -Force
# this will populate the list with data of the list
Add-PnPDataRowsToSiteTemplate -Path "C:\TempDemo.xml" -List "testList"