The remote server returned an error: (401) Unauthorized - CSOM - OAuth - after specific time

Question

I am trying to get permissions assigned to each document from the document library using csom in console application. Console app is running fine for almost one hour and post that I get error : "The remote server returned an error: (401) Unauthorized."

I registered an app in SharePoint and I'm using Client ID & Client Secret Key to generate Client Context. Here is the code to get the client context

public static ClientContext getClientContext()
    {
        ClientContext ctx = null;
        try
        {
            ctx = new AuthenticationManager().GetAppOnlyAuthenticatedContext(SiteUrl, ClientId, ClientSecret);
            ctx.RequestTimeout = 6000000;

            ctx.ExecutingWebRequest += delegate (object sender, WebRequestEventArgs e)
            {
                e.WebRequestExecutor.WebRequest.UserAgent = "NONISV|Contoso|GovernanceCheck/1.0";
            };
        }
        catch (Exception ex)
        {
            WriteLog("Method-getClientContext, Error - " + ex.Message);
        }
        return ctx;
    }

Here is the code which is getting all the assignments assigned to document in document library.

static StringBuilder excelData = new StringBuilder();            
static void ProcessWebnLists()
    {
        try
        {
            string[] lists = { "ABC", "XYZ", "DEF", "GHI"};

            foreach (string strList in lists)
            {
                using (var ctx = getClientContext())
                {
                    if (ctx != null)
                    {
                        Web web = ctx.Site.RootWeb;
                        ListCollection listCollection = web.Lists;
                        ctx.Load(web);
                        ctx.Load(listCollection);
                        ctx.ExecuteQuery();

                        List list = web.Lists.GetByTitle(strList);
                        ctx.Load(list);
                        ctx.ExecuteQuery();

                        Console.WriteLine("List Name:{0}", list.Title);

                        var query = new CamlQuery { ViewXml = "<View/>" };

                        var items = list.GetItems(query);
                        ctx.Load(items);
                        ctx.ExecuteQuery();

                        foreach (var item in items)
                        {
                            var itemAssignments = item.RoleAssignments;
                            ctx.Load(item, i => i.DisplayName);
                            ctx.Load(itemAssignments);
                            ctx.ExecuteQuery();
                            Console.WriteLine(item.DisplayName);
                            string groupNames = "";
                            foreach (var assignment in itemAssignments)
                            {
                                try
                                {
                                    ctx.Load(assignment.Member);
                                    ctx.ExecuteQuery();
                                    groupNames += "[" + assignment.Member.Title.Replace(",", " ") + "] ";
                                    Console.WriteLine($"--> {assignment.Member.Title}");
                                }
                                catch (Exception e)
                                {
                                    WriteLog("Method-ProcessWebnLists, List-" + list.Title + ", Document Title - " + item.DisplayName + ", Error : " + e.Message);
                                    WriteLog("Method-ProcessWebnLists, StackTrace : " + e.StackTrace);
                                }
                            }
                            excelData.AppendFormat("{0},{1},ITEM,{2}", list.Title, (item.DisplayName).Replace(",", " "), groupNames);
                            excelData.AppendLine();
                        }
                    }
                    excelData.AppendLine();
                }
            }
        }
        catch (Exception ex)
        {
            WriteLog("Method-ProcessWebnLists, Error : " + ex.Message);
            WriteLog("Method-ProcessWebnLists, StackTrace : " + ex.StackTrace.ToString());
        }
    }

Can anyone suggest what else I am missing in this or what kind of changes do I need to make to avoid this error?

The process is taking too much time so I want my application to keep running for couple of hours.

Thanks in advance!

RockinRowl RockinRowl · Accepted Answer · 2018-07-20T01:21:20

Is there a reason why getClientContext() is inside the foreach loop?

I encountered this error before. I added this to solve mine.

public static void ExecuteQueryWithIncrementalRetry(this ClientContext context, int retryCount, int delay)
{
    int retryAttempts = 0;
    int backoffInterval = delay;
    if (retryCount <= 0)
        throw new ArgumentException("Provide a retry count greater than zero.");
   if (delay <= 0)
        throw new ArgumentException("Provide a delay greater than zero.");
   while (retryAttempts < retryCount)
    {
        try
        {
            context.ExecuteQuery();
            return;
        }
        catch (WebException wex)
        {
            var response = wex.Response as HttpWebResponse;
            if (response != null &amp;&amp; response.StatusCode == (HttpStatusCode)429)
            {
                Console.WriteLine(string.Format("CSOM request exceeded usage limits. Sleeping for {0} seconds before retrying.", backoffInterval));
                //Add delay.
                System.Threading.Thread.Sleep(backoffInterval);
                //Add to retry count and increase delay.
                retryAttempts++;
                backoffInterval = backoffInterval * 2;
            }
            else
            {
                throw;
            }
        }
    }
    throw new MaximumRetryAttemptedException(string.Format("Maximum retry attempts {0}, have been attempted.", retryCount));
}

Basically, this code backs off for a certain time/interval before executing another query, to prevent throttling.

So instead of using ctx.ExecuteQuery(), use ctx.ExecuteQueryWithIncrementalRetry(5, 1000);

Further explanation here https://docs.microsoft.com/en-us/sharepoint/dev/general-development/how-to-avoid-getting-throttled-or-blocked-in-sharepoint-online

The remote server returned an error: (401) Unauthorized - CSOM - OAuth - after specific time

1 Answers