Errors with downloading files from SharePoint in an Azure Function App

[WoodyDev1]

Hi,
I have a business need where I need to create an Azure Function App to download specific files from SharePoint (SP) and then do what we need with them. I am using the Function App's Managed Identity (MI) to connect and that works fine. I have given my MI the SharePoint permissions of Sites.FullControl.All (might change later if needed).

Yesterday (19th August 2025), the script worked fine. I was able to connect to SP and download the file using Get-PnPFile -Url $sharePointFileUrl -Path $env:TEMP -FileName $fileName -AsFile -Force fine and then do what I need. However, today all of a sudden nothing worked. I have spent countless hours trying to resolve with different error messages and now the latest which I've been stuck on for ages is the below;

ERROR: Failed to download file from SharePoint: SharePoint Rest service exception Exception : Type : Microsoft.PowerShell.Commands.WriteErrorException Message : Failed to download file from SharePoint: SharePoint Rest service exception HResult : -2146233087 CategoryInfo : NotSpecified: (:) [Write-Error], WriteErrorException FullyQualifiedErrorId : Microsoft.PowerShell.Commands.WriteErrorException,_PropelITFileTransfer_ InvocationInfo : MyCommand : _PropelITFileTransfer_ HistoryId : 1 InvocationName : _PropelITFileTransfer_ CommandOrigin : Internal ScriptStackTrace : at <ScriptBlock>, C:\home\site\wwwroot\PropelITFileTransfer\run.ps1: line 110

I have tried a few things like changing the authentication to use a certificate but that didn't work so I'm back at my MI, I have tried different files in the same location as well as different SP sites but still same error.

Any ideas to get this resolved would be greatly appreciated!
Thanks.