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How to resolve issues editing Microsoft Office files from SharePoint when ESP is enabled

Updated: August 16, 2021 20:59

Scope

When utilizing Kemp's Edge Security Pack (ESP) feature with SharePoint (SP), you may run into an issue whereby you are unable to edit your Microsoft Office files. This is because the Office file has no Authentication Cookie associated with it. So in turn, the LoadMaster redirects the client to the LoadMaster’s ESP Auth-Proxy page to authenticate. 

You will either receive the following error:

Or you will see the Kemp login form within Microsoft Excel or Word: 

 

With SAML set as your Client-Side Authentication, your Office file might just hang and eventually show the below message. This is because ESP redirects you to ADFS due to a missing Authentication Cookie. 

 

Solution

1. Enable Permanent Cookies on your SharePoint Virtual Service under ESP Options. 
2. Configure Internet Explorer to Accept Third Party Cookies and add the SP site to your Trusted Sites. 

Note: This solution only works if clients are using Internet Explorer. This is because Chrome and Firefox and Edge are unable to associate authentication cookies with MS Office files. 

If you have no control over external clients and they use Chrome or Firefox, then you will need to install an Office Online Server. 

 

Configuration

1. Enable Permanent Cookies on your SharePoint Virtual Service under ESP Options. 

For more information on Permanent Cookies, refer to the following article:  What Does The Use Session Or Permanent Cookies Option Mean?

 

Note: If you select Permanent Cookies only on Private Computers, you must ensure that your client always selects This is a private computer when logging in: 

 

 

Note: When SAML is configured, you must select Permanent Cookies Always:

 

 

2. Add the SP site to your trusted sites: 

IE > Internet Options > Security > Trusted Sties 

3. Configure Third Party Cookies:

IE > Internet Options > Privacy > Advanced

 

Related Knowledgebase Article:

What Does The Use Session Or Permanent Cookies Option Mean?

 

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