Sharepoint 2007 Powershell: $item.update() gives error that file has been modified

Question

I am trying to programmatically update some metadata for a sharepoint item using powershell. Here is my code:

$web = getWebByURL("http://test-site/spadmin/")
$itm = $web.lists["Documents"].items[0]
$itm["Description"] = "This is a test edit"
$spfields = "Modified", "Created"
    foreach($fieldname in $spfields){
        $itm.parentList.Fields[$fieldname].ReadOnlyField = $false;
        $itm.parentList.Fields[$fieldname].update()

        $itm[$fieldname] = $sourceItm[$fieldname].toString()

        $itm.parentList.Fields[$fieldname].ReadOnlyField = $true;
        $itm.parentList.Fields[$fieldname].update()

    }
$itm["Author"] = $sourceItm["Author"].toString()
$itm["Editor"] = $sourceItm["Editor"].toString()
$itm.updateOverwriteVersions()
# Also tried $itm.update()
# Also tried $itm.systemUpdate()

Error:

Exception calling "SystemUpdate" with "0" argument(s): "The file Documents/1test.doc has
been modified by Domain\myusername on <date time stamp>."

I have tried to re get a handle on the item using

$itm = $itm.parentList.getItemById($itm.id)

I have tried to enable/disable unsafeupdates

$itm.parentList.parentWeb.AllowUnsafeUpdates = $true

Am I missing something here or going about this the wrong way? Please help!!

Answer 1

recently I had similar error but with C# code. The reason was an event receiver set on the library.

When event receiver is set to library (item updated for example) and you try to update the item to avoid indefinite call of item update this exception is thrown.

Try to see if there is event receiver is attached to the library and if it is a case, you should edit event receiver temporary to disable event firing while you update is in progress using next Property of event receiver:

EventFiringEnabled = true|false;

Do not forget to renable event firing. If not - not events will be fired.

Hope it helps,

Andrew

Answer 2

My guess is that you are actually getting a missleading error, because the Modified and Created fields are automatically maintained by SharePoint and you should never try to update their values in any way.

In addition to that, you are actually doing 2 update operations, one to attempt to change the field Read-Only status and then you actually try to UpdateOverwrite the data. You should separate these 2 operations already, by retrieving once again a reference to the List before running the 2nd update (this, just in case where you want to try with other fields).