Error Updating Metadata on xlsx Documents using PowerShell

Question

I'm able to update metadata associated with PDF's and other file types, but I'm not able to update metadata associated with xlsx documents. On the xlsx docs, the error is thrown when the $item.Update() method is called.

function updateDemoItem
{
  param (
    [Microsoft.SharePoint.SPList]$list, 
    [Microsoft.SharePoint.SPItem]$item
  )

  $item.File.CheckOut()
  $item[“DemoStringField”] = “new value”
  $item.Update()    
  $item.File.CheckIn("Demo Update Item")
  $item = $list.GetItemById($item.id)   
  return $item

}

Error:

    System.Management.Automation.MethodInvocationException: Exception calling "Update" with "0" argument(s): "This item cannot be updated because it is locked as read-only." ---> Microsoft.SharePoint.SPException: This item cannot be updated because it is locked as read-only. ---> System.Runtime.InteropServices.COMException (0x81020089): <nativehr>0x81020089</nativehr><nativestack></nativestack>This item cannot be updated because it is locked as read-only.
   at Microsoft.SharePoint.Library.SPRequestInternalClass.AddOrUpdateItem(String bstrUrl, String bstrListName, Boolean bAdd, Boolean bSystemUpdate, Boolean bPreserveItemVersion, Boolean bPreserveItemUIVersion, Boolean bUpdateNoVersion, Int32& plID, String& pbstrGuid, Guid pbstrNewDocId, Boolean bHasNewDocId, String bstrVersion, Object& pvarAttachmentNames, Object& pvarAttachmentContents, Object& pvarProperties, Boolean bCheckOut, Boolean bCheckin, Boolean bMigration, Boolean bPublish, String bstrFileName, ISP2DSafeArrayWriter pListDataValidationCallback, ISP2DSafeArrayWriter pRestrictInsertCallback, ISP2DSafeArrayWriter pUniqueFieldCallback)
   at Microsoft.SharePoint.Library.SPRequest.AddOrUpdateItem(String bstrUrl, String bstrListName, Boolean bAdd, Boolean bSystemUpdate, Boolean bPreserveItemVersion, Boolean bPreserveItemUIVersion, Boolean bUpdateNoVersion, Int32& plID, String& pbstrGuid, Guid pbstrNewDocId, Boolean bHasNewDocId, String bstrVersion, Object& pvarAttachmentNames, Object& pvarAttachmentContents, Object& pvarProperties, Boolean bCheckOut, Boolean bCheckin, Boolean bMigration, Boolean bPublish, String bstrFileName, ISP2DSafeArrayWriter pListDataValidationCallback, ISP2DSafeArrayWriter pRestrictInsertCallback, ISP2DSafeArrayWriter pUniqueFieldCallback)
   --- End of inner exception stack trace ---
   at Microsoft.SharePoint.SPGlobal.HandleComException(COMException comEx)
   at Microsoft.SharePoint.Library.SPRequest.AddOrUpdateItem(String bstrUrl, String bstrListName, Boolean bAdd, Boolean bSystemUpdate, Boolean bPreserveItemVersion, Boolean bPreserveItemUIVersion, Boolean bUpdateNoVersion, Int32& plID, String& pbstrGuid, Guid pbstrNewDocId, Boolean bHasNewDocId, String bstrVersion, Object& pvarAttachmentNames, Object& pvarAttachmentContents, Object& pvarProperties, Boolean bCheckOut, Boolean bCheckin, Boolean bMigration, Boolean bPublish, String bstrFileName, ISP2DSafeArrayWriter pListDataValidationCallback, ISP2DSafeArrayWriter pRestrictInsertCallback, ISP2DSafeArrayWriter pUniqueFieldCallback)
   at Microsoft.SharePoint.SPListItem.AddOrUpdateItem(Boolean bAdd, Boolean bSystem, Boolean bPreserveItemVersion, Boolean bNoVersion, Boolean bMigration, Boolean bPublish, Boolean bCheckOut, Boolean bCheckin, Guid newGuidOnAdd, Int32& ulID, Object& objAttachmentNames, Object& objAttachmentContents, Boolean suppressAfterEvents, String filename, Boolean bPreserveItemUIVersion)
   at Microsoft.SharePoint.SPListItem.UpdateInternal(Boolean bSystem, Boolean bPreserveItemVersion, Guid newGuidOnAdd, Boolean bMigration, Boolean bPublish, Boolean bNoVersion, Boolean bCheckOut, Boolean bCheckin, Boolean suppressAfterEvents, String filename, Boolean bPreserveItemUIVersion)
   at Microsoft.SharePoint.SPListItem.Update()
   at Update(Object , Object[] )
   at System.Management.Automation.DotNetAdapter.AuxiliaryMethodInvoke(Object target, Object[] arguments, MethodInformation methodInformation, Object[] originalArguments)
   --- End of inner exception stack trace ---
   at System.Management.Automation.DotNetAdapter.AuxiliaryMethodInvoke(Object target, Object[] arguments, MethodInformation methodInformation, Object[] originalArguments)
   at System.Management.Automation.ParserOps.CallMethod(Token token, Object target, String methodName, Object[] paramArray, Boolean callStatic, Object valueToSet)
   at System.Management.Automation.MethodCallNode.InvokeMethod(Object target, Object[] arguments, Object value)
   at System.Management.Automation.MethodCallNode.Execute(Array input, Pipe outputPipe, ExecutionContext context)
   at System.Management.Automation.ParseTreeNode.Execute(Array input, Pipe outputPipe, ArrayList& resultList, ExecutionContext context)
   at System.Management.Automation.StatementListNode.ExecuteStatement(ParseTreeNode statement, Array input, Pipe outputPipe, ArrayList& resultList, ExecutionContext context)

Answer 1

The file is locked or checkout by another user. Just check if that is the case and then UndoCheckout as below

#Discard any check-out
if ($item.File -ne $null -and $item.File.CheckOutType -ne [Microsoft.SharePoint.SPFile+SPCheckOutType]::None)
{
  $item.File.UndoCheckOut()
}

Answer 2

Turns out, a content type was incorrectly created / published and it was causing some updates to fail.

We have a desktop app that creates content types across a site collections. In the app, a config value was incorrectly configured.