The security validation for this page is invalid error trying to add sharepoint approval workflow to List in ListAdded eventreceiver - sharepoint-2010

Question

What I am trying to do is to attach the OOTB sharepoint workflow [Approval Sharepoint - 2010] to each and every document library that ever gets created. To accomplish this I created a List Added event reciever and put this code in it -
public override void ListAdded(SPListEventProperties properties)
{
SPSecurity.RunWithElevatedPrivileges(delegate()
{
SPUtility.ValidateFormDigest();
using (SPSite site = new SPSite(properties.SiteId))
{
using (SPWeb web = site.OpenWeb())
{
try
{
base.ListAdded(properties);
if (currentList is SPDocumentLibrary)
{
SPDocumentLibrary docLib = (SPDocumentLibrary)properties.List;
//workflows need a tasks and history list. Here we assume they exist
SPList taskList = web.Lists["Tasks"];
SPList historyList = web.Lists["Workflow History"];
//loop through the workfows in the web and grab the one we want by name
SPWorkflowTemplate wfTemp = null;
foreach (SPWorkflowTemplate wt in web.WorkflowTemplates)
{
if (wt.Name == "Approval - SharePoint 2010")
{
wfTemp = wt;
Common.AddToLog(web, "Found " + wt.Name + " in current web " +
web.Url, false);
break;
}
}
//Now add the workflow to the doc library
SPWorkflowAssociation workFlow = SPWorkflowAssociation.CreateListAssociation(wfTemp, wfTemp.Name, taskList, historyList);
workFlow.AllowManual = true;
workFlow.AutoStartChange = false;
workFlow.AutoStartCreate = true;
workFlow.AssociationData = null;
web.AllowUnsafeUpdates = true;
web.ValidateFormDigest();
docLib.WorkflowAssociations.Add(workFlow);
docLib.EnableModeration = true;
docLib.Update();
web.Update();
web.AllowUnsafeUpdates = false;
}
}
catch (Exception ex)
{
throw ex;
}
finally
{
web.AllowUnsafeUpdates = false;
}
}
}
});
}
I am getting this error-
The security validation for this page is invalid. Click Back in your Web browser, refresh the page, and try your operation again.
at this line
docLib.WorkflowAssociations.Add(workFlow);
Any any have any suggestions please ? Thanks for your feedback.

Answer 1

Why do you need "SPUtility.ValidateFormDigest()" at all?
Your code was running in an event receiver, not on a form or aspx page, there is nothing to validate.
Could you remove this line and try again?

Answer 2

I believe updating this code block:
web.AllowUnsafeUpdates = true;
web.ValidateFormDigest();
docLib.WorkflowAssociations.Add(workFlow);
docLib.EnableModeration = true;
docLib.Update();
web.Update();
web.AllowUnsafeUpdates = false;
and replacing it with:
web.Site.WebApplication.FormDigestSettings.Enabled = false;
docLib.WorkflowAssociations.Add(workFlow);
docLib.EnableModeration = true;
docLib.Update();
web.Update();
web.Site.WebApplication.FormDigestSettings.Enabled = true;
Let me know if this works for you or if you still encounter the same error.