SharePoint 2013 - 401 Unauthorized error

Question

Hi, 

Recently I was attempting to brand a clients SharePoint 2013 site. After I deployed the solution, set it to custom/default master page and suddenly I get "Unauthorized 401" all over the place with URL "start.aspx". I looked around and found out that this only happened when having the "Minimal Download Strategy" site feature enabled and SharePoint run the request through the start.aspx page.

After I disabled the MDS Feature, then I am able to open site home page, document library again. I don't know what is the the real reason for such error.

MS best practice it to disable the MDS Featue? Or any suggestion? What is the root cause for such error?

Hope someone here can assist me.

Answer 1

Hi,

This feature cause issues like access denied as anonymous users do not have access to _layouts folder by default.

Are you getting Access denied for Anonymous users?

Regards,

Amit

Answer 2

Hi Amit,

User have access to the site and getting "Unauthorized 401" but not access denied. 

Thanks.

Answer 3

Hi John,

Yes, "Minimal Download Strategy" feature could cause the 401 unauthorized error.

I would suggest you can disable the feature if possible.

Here are some detailed articles specified this issue:

401 Unauthorized errors on SharePoint 2013

How to Disable Minimal Download Strategy (MDS) in SharePoint 2013 

Thanks

Best Regards

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