Category / Features

by Simon Doy

Feature Upgrade Issue: Deleted SPWebs : An error occurred while enumerating through a collection


Introduction

Recently I published a post about issues when upgrading Site Scope features in SharePoint. The issue was related to deleted Site Collections which were still in the recycle bin.

After resolving this issue I decided to do some testing with other deleted SharePoint objects. The next logical object type to delete was an SPWeb object.

Unfortunately further issues were found and the following section explains how they were found and the approach to resolve them.

 

How the Issue was Approached

The approach taken was the following:-

  • Build a Web Scoped Feature marked v1.0.0.0
  • Install the SharePoint Solution
  • Create a number of Webs and Activate the feature on those webs
  • Delete one of the Webs
  • Update the Web Scoped Feature to v2.0.0.0
  • Upgrade the SharePoint Solution to deploy the new version of the Web Scoped Feature
  • Use Install-SPFeature [FeatureName] –Force to upgrade the feature
  • Run a PowerShell command to execute the SPSite.QueryFeatures() function

The following PowerShell was run to query for Features that need to be upgraded.

 $site=Get-SPSite http://sharepoint; $site.QueryFeatures("Web", $true);

The result of the script displayed the following:-

 $site.QueryFeatures("Web",$true);  An error occurred while enumerating through a collection: Unable to access web scoped feature (Id: f41cc668-37e5-4743-b4a8-74d1db3fd8a4) because it references  a non-existent or broken web (Id: 3bd828cf-b747-4111-b888-5953b0d9aaa3) on sit e 'http://dev.itsp.local'.  Exception: System.ArgumentException: Value does not  fall within the expected range.    at Microsoft.SharePoint.SPWebCollection.get_Item(Guid id)    at Microsoft.SharePoint.SPFeatureEnumeratorBase.GetCachedWeb(SPSite site, Gu id webId, Guid featureId). At line:1 char:20 + $site.QueryFeatures >> ("Web",$true)     + CategoryInfo          : InvalidOperation: (Microsoft.Share...esultCollec    tion:SPFeatureQueryResultCollection) [], RuntimeException     + FullyQualifiedErrorId : BadEnumeration

 

Solution

The approach to solving this issue was not to write a workaround but to run a script which checks for deleted SPWeb objects in the site collection.

 $site = Get-SPSite http://sharepoint; $site.RecycleBin | ?{$_.ItemType -eq "Web"};

The script will display the SharePoint Web Objects that have been deleted and are still found in the site collections recycle bin.

The deleted SPWeb objects can be removed from the recycle bin using the following PowerShell command. 

 $site = Get-SPSite http://sharepoint;  $deletedWebs = $site.RecycleBin | ?{$_.ItemType -eq "Web"}; $deletedWebs | % {$site.RecycleBin.Delete($_.Id)}

This will delete the SPWeb objects from the recycle bin and the Feature Upgrade process can continue.

Please be careful when running this script! Only run it when you know that none of the SharePoint Web sites are not needed!

 

Anyway hope that helps!

by Simon Doy

Creating List Instance: Object Reference not set to an instance of an object


Introduction

This one is a bit of an old issue but some of my posts are just to remind me of a time that I got stuck in the past. Also if it helps someone else then great.

It is possible to create a feature which creates an instance of a SharePoint List when its activated. However, sometimes you only want a list to be created on the Root Web of a site collection.

Issue

Well the XML for specifying a ListInstance as a feature has an attribute called RootWebOnly which I thought I could use to only allow the ListInstance to be created on the RootWeb.

Unfortunately when you do that you get a message like the following in your SharePoint ULS Logs when the feature is activated:-

Feature Activation: Threw an exception, attempting to roll back. Feature ‘FeatureName’(ID: ‘xxxxxxxx-xxxx-xxxx-xxxxxxxx). Exception: System.NullReferenceException: Object reference not set to an instance of an object.
at Microsoft.SharePoint.SPListInstanceElement.ElementActivated(SPFeaturePropertyCollection props, SPSqlCommand sqlcmdAppendOnly, SPWebApplication webApp, SPSite site, SPWeb web, Boolean fForce)
at Microsoft.SharePoint.Administration.SPElementDefinitionCollection.ProvisionListInstances(SPFeaturePropertyCollection props, SPSite site, SPWeb web, Boolean fForce)
at Microsoft.SharePoint.Administration.SPElementDefinitionCollection.ProvisionElements(SPFeaturePropertyCollection props, SPWebApplication webapp, SPSite site, SPWeb web, Boolean fForce)
at Microsoft.SharePoint.SPFeature.ProvisionElements(SPFeaturePropertyCollection props, SPWebApplication webapp, SPSite site, SPWeb web, Boolean fForce)
at Microsoft.SharePoint.SPFeature.Activate(SPSite siteParent, SPWeb webParent, SPFeaturePropertyCollection props, Boolean fForce)

The offending Feature ListInstance element is below:-

 1: <?xmlversion="1.0" encoding="utf-8"?>
 2: <Elements
 3: xmlns="http://schemas.microsoft.com/sharepoint/">
 4: <ListInstance
 5: Id="AListId"
 6: Title="A List"
 7: Description="A List 
 8: Description”
 9: Url="Lists/ListUrlHere"
 10: OnQuickLaunch="FALSE"
 11: RootWebOnly=”TRUE”
 12: FeatureId="xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxx"
 13: TemplateType="45100"></ListInstance>
 14: </Elements>

Solution

To fix the feature activation remove the RootWebOnly=”TRUE” from your ListInstance element manifest file and instead move the RootWebOnly=”TRUE” into your List’s schema.xml.

To ensure that the list is only provisioned at the root web of the site collection change the Feature.xml to use Scope=”Site”

Update:

Thanks to Dennis who picked up my mistake in this post which stated that the RootWebOnly attribute should be moved to the feature.xml.