Summary

This article describes how to resolve an Error Message "Operation Failed: Error Creating User. Details: Error Adding User in Site Collection: The User Does Not Exist or Is Not Unique  " (snapshot attached) which normally appears while creating SharePoint user as visitor and member.

Applies To

MachPanel all versions.
Office SharePoint Server 2007.

Symptoms

User creation fails while creating SharePoint user as Visitor or Member.

Solution

The mentioned issue can be resolved by disabling a Policy. It is a local policy in Windows Server 2008 R2 that is required to be disabled (and machine restart is required after reset). This policy name is "Domain member: Digitally encrypt or sign secure channel data (always)" which is enabled by default when you configure Windows Server 2008 R2. This desired operation can be successfully done by performing the following steps:

1. Go to Group Policy Editor (Start -> Run -> type gpedit.msc)
2. Browse to the following location
   
   • Computer Configuration -> Windows Settings -> Security Settings -> Local Policies -> Security Options
3. Under Security Options on the right hand side, you will find the desired policy
   
   • Double click to open the policy
   • Click 'Disable' radio option
   • Save the changes
   • And restart the machine

This way, the desired task can be performed successfully and the error message will be resolved immediately.