Locked Workflow

I've periodically come across this SPException: "This task is currently locked by a running workflow and cannot be edited" when using the SPWorkflowTask.AlterTask method, even when it seems that the workflow is not in fact locked, and is instead patiently listening for an OnTaskChangedEvent. It turns out that this exception is thrown when the WorkflowVersion of the task list item is not equal to 1, which, if you believe the error message is the same thing as checking to see if the workflow is locked. Only it isn't - apparently sometimes at least, the Workflow version is non zero and the workflow is not locked (the InternalState flag of the workflow does not include the Locked flag bits). I'm not sure why this is occurring - maybe the error message is misleading - but the following code demonstrates a dodgy sort of a workaround that I've found useful. I've no idea if this is a good idea or not, so please treat with skepticism...

using System;

using Microsoft.SharePoint;

using Microsoft.SharePoint.Workflow;

using System.Collections;

using System.Threading;

namespace DevHoleDemo

{

    public class WorkflowTask

    {

        public static bool AlterTask(SPListItem task, Hashtable htData, bool fSynchronous, int attempts, int millisecondsTimeout)

        {

            if ((int)task[SPBuiltInFieldId.WorkflowVersion] != 1)

            {

                SPList parentList = task.ParentList.ParentWeb.Lists[new Guid(task[SPBuiltInFieldId.WorkflowListId].ToString())];

                SPListItem parentItem = parentList.Items.GetItemById((int)task[SPBuiltInFieldId.WorkflowItemId]);

                for (int i = 0; i < attempts; i++)

                {

                    SPWorkflow workflow = parentItem.Workflows[new Guid(task[SPBuiltInFieldId.WorkflowInstanceID].ToString())];

                    if (!workflow.IsLocked)

                    {

                        task[SPBuiltInFieldId.WorkflowVersion] = 1;

                        task.SystemUpdate();

                        break;

                    }

                    if (i != attempts - 1)

                        Thread.Sleep(millisecondsTimeout);

                }

            }

            return SPWorkflowTask.AlterTask(task, htData, fSynchronous);

        }

    }

}