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

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.