Sharepoint Migration Missing assembly

This article describes solution of Missing assembly issue

MissingAssembly Error

MissingAssembly errors look similar to this one:

Category : MissingAssembly
Error : True
UpgradeBlocking : False

Message : Assembly [PAC.SharePoint.Tagging, Version=1.0.0.0, Culture=neutral, PublicKeyToken=b504d4b6c1e1a6e5] is referenced in the database [SP2010_Content], but is not installed on the current farm. Please install any feature/solution which contains this assembly.

Remedy : One or more assemblies are referenced in the database [SP2010_Content], but are not installed on the current farm. Please install any feature or solution which contains these assemblies.

I normally find MissingAssembly errors appear as the result of an event receiver, which is still registered on a list or library but part of a feature/solution no longer present on the farm.

In most cases, you may be able to look at the assembly name reported in this error and know what the problem is straight away. As before, the best way of resolving this is to reinstall the missing solution file. However, if you are not able to install the solution (e.g., maybe it only works in SharePoint 2007 and not 2010), then you may want to find the lists where the event receiver is installed and either remove the event receiver from the lists or delete the lists themselves.

To troubleshoot this issue we can re-use the Run-SQLQuery function used to help find missing web parts above. The table we need to look at this time though is called “EventReceivers”. For example, you would type the following command to find details of the assembly called “PAC.SharePoint.Tagging, Version=1.0.0.0, Culture=neutral, PublicKeyToken=b504d4b6c1e1a6e5”, as reported in the error above:


Run-SQLQuery -SqlServer "SQLSERVER" -SqlDatabase "SP2010_Content" -SqlQuery "SELECT * from EventReceivers where Assembly = ‘PAC.SharePoint.Tagging, Version=1.0.0.0, Culture=neutral, PublicKeyToken=b504d4b6c1e1a6e5'" | select Id, Name, SiteId, WebId, HostId, HostType | Format-List

This will produce an output similar to the following:

Id : 657a472f-e51d-428c-ab98-502358d87612
Name :
SiteId : 337c5721-5050-46ce-b112-083ac52f7f26
WebId : 2ae0de59-a008-4244-aa66-d8f76c79f1ad
HostId : 09308020-45a8-41e4-bbc0-7c8d8cd54132
HostType : 2

As with the MissingWebPart error before, we can use these GUIDs to get the site collection and site hosting the list with the missing event receiver, as follows:

$site = Get-SPSite -Limit all | where {$_.Id -eq "337c5721-5050-46ce-b112-083ac52f7f26"}
$web = $site | Get-SPWeb -Limit all | where {$_.Id -eq "2ae0de59-a008-4244-aa66-d8f76c79f1ad"}
$web.Url

The HostId property is the GUID of the object containing the event receiver. The HostType is the object type – in this case, HostType “2” means the event receiver host is a list.
You can look at the other host types by checking this article on MSDN: http://msdn.microsoft.com/en-us/library/ee394866(v=prot.13).aspx.

Now we know the GUID refers to a list, we can get it using PowerShell with this command:

$list = $web.Lists | where {$_.Id -eq "09308020-45a8-41e4-bbc0-7c8d8cd54132"}

To remove the list completely, type the following command:

$list.Delete()

To keep the list intact and just remove the offending event receiver, copy the Id property from the Run-SQLQuery output into this command:

$er = $list.EventReceivers | where {$_.Id -eq "657a472f-e51d-428c-ab98-502358d87612"}
$er.Delete()

If you do decide to delete the list completely, ensure you also remove it from the site Recycle Bin and Site Collection Recycle Bin to ensure the file is removed from the content database.
If not, the error may not disappear from the Health Analyzer or Test-SPContentDatabase operation.