I am running on-Prem Sharepoint 2013 and writing a web application that will access SharePoint lists using CSOM.

I am using Claims Authentication and have Anonymous Access allowed for the web app.

Here are the first few line of CSOM:

    Dim ouritems As ListItemCollection
    Using cc As New ClientContext(siteURL)
        Dim ourList As List = cc.Web.Lists.GetByTitle(listTitle)

Everything is working just fine.

I now turn Anonymous Access off.

My ExecuteQuery (the first access to SharePoint in the application) now fails with an exception: Too many redirections were attempted.

Can anyone explain the connection between turning of Anonymous Access and the exception?

1 Answer 1


Here's the answer. I went to IIS to check the options there for my SharePoint web app and noticed that Forms Authentication was enabled. As this web app is only for an intranet, I turned Forms Authentication off.

That broke everything. Eventually I found this article that explains that even though the application is using Claims Authorization, somewhere deep in SharePoint, Forms Authentication is required!


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