2523305 - The HTTP request was forbidden with client authentication scheme 'Negotiate'.

The following error is being returned when attempting to submit data via an Input schedule in the EPM Add-in:

Framework message:
The HTTP request was forbidden with client authentication scheme 'Negotiate'.

Access Denied

Server message:

code :
severity : error
description : You are not authorized to perform this task; contact your system administrator
log id :
-----------------

Framework message:
The remote server returned an error: (403) Forbidden.

The HTTP request was forbidden with client authentication scheme 'Negotiate'.
The remote server returned an error: (403) Forbidden.

Upon inspecting the tblLogs table in the Appserver database, the following error is recorded:

==============[System Exception Tracing]==============

[System Name] : /SAP/BPC/Comments.svc
[Message Type] : ErrorMessage
[Job Name] : CheckTaskSecurity
[DateTime] : 08/22/2017 09:56:56
[UserId] : <server name>\<user id>
[Exception]
DetailMsg : {You are not authorized to perform this task; contact your system administrator.(UserID: [<server name>\<user id>], Appset: [<Environment Name>], Service: [SAP.BPC.Services.Webservice.Comments], Method: [WriteComments])}
==============[System Exception Tracing End ]==============

• SAP EPM Add-in for Microsoft Office
• SAP Business Planning and Consolidation for Microsoft version 10.x

KBA , EPM-BPC-MS , Microsoft Version , Problem