Equisys technical notes

Technical guidance, explanations and fixes for our products

PRB: Zetadocs Expenses report fails to export with error in logs: 'The authentication header received from the server was "NTLM". '



This Zetadocs technical note applies to:

  • Zetadocs Expenses Connector using the Business Central Extension- all versions
  • All versions of Business Central On-Premises


When you are experiencing issues exporting expenses into your Business Central environment when you are using the Expenses Connector and you see the following error within the ZetadocsExpense.log file:

The connector logs show the following error:

Error 16 ConnectorCore.GetVersion[152] Exception was thrown 'The HTTP request is unauthorized with client authentication scheme 'Negotiate'. The authentication header received from the server was 'NTLM'.' of type System.ServiceModel.Security.MessageSecurityException, System.ServiceModel, Version=, Culture=neutral, PublicKeyToken=b77a5c561934e089;Connector Request: GetBusinessCentralVersion


The reason for this is that the Business Central server is trying to use NTLM to communicate with the Zetadocs Expenses Connector but it is not supported.


In the Zetadocs Expenses Connector config file located in the install folder (e.g. C:\Program Files (x86)\Zetadocs Expenses Connector\Zetadocs.Approval.Connector.exe.config) search for the "clientCredentialType" settings and make sure they are set to "Windows" and then restart the Zetadocs Expenses Connector Service and retry the export.

If it still gives the same error in the logs then in the Business Central Adminsitration Settings, go to the General section and make sure that the "Use NTLM Authentication" setting is not enabled. Then restart the Business Central service. 
This is will turn off NTLM authentication for the whole Business Central instance. If you do need NTLM enabled for anything else you'll need to setup a new instance of Business Central for Zetadocs Expenses to use that doesn't have this "Use NTLM Authentication" setting enabled.


Equisys is aware of this issue and will update this technical note when a solution has been found..

Last updated: 21st July 2021  (MP/NT) 

Keywords: Zetadocs Expenses Connector, NTLM

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