Exchange 2019: Clients Are Not Connecting

Customer deployed new Exchange server 2019 on a new Active Directory Forest.

They were using Outlook 2013 32 bit on Windows 7


While creating new profile on outlook got the following error:

“The connection to the Microsoft Exchange Server is unavailable. Outlook must be online or connected to complete this action.”


OWA denied the page loading


  • Found External URLs were not configured and internal URLs were using domain.local as the fqdn.

    As domain.local is non routable public domain so updated all the url with public routable urls and added external URLs.

  • Found there was no SSL certificate so exported and imported SSL certificate to Exchange 2019.

    Now OWA started working.

  • Outlook was still giving the same error.
    • Unchecked the basic authentication on Mapi Virtual Directory which was checked.

    On the client side.

    • Installed latest Office 32013 update
    • Add the following registry key to enable the Encryption between client and server for RPC.

    DWORD: EnableRPCEncryption
    Value: 1

    • Add the following registry key to point it to the correct directory services server.

    “HKEY_CURRENT_USER\Software\Microsoft\Exchange\Exchange Provider

    String Value (REG_SZ): DS Server

    Value: DC01.Domainname.LOCAL

This resolved the issue.

Prabhat Nigam
CEO @ LAEXUG Foundation | CTO @ Golden Five Consulting |

CTO @ Golden Five | CEO at LAExUG Foundation

Prabhat is 3 times Microsoft MVP Award winner. He is MBA in Information Technology and he is working as a CTO at Golden Five Consulting which is a Microsoft Gold Partner, MSP, T1CSP, and Education partner. He helps in designing, implementing, managing and supporting solutions for private messaging cloud, mergers, a collaboration between different messaging software and other migration & deployment projects for the following technologies Office 365, Azure, AWS, Exchange, SQL, ADFS, MFA, FIM, MIM and Directory services. He has worked for all big IT giants either as an employee or contractor where he has led the Global teams. He has started his career as Technical Consultant in Exchange 5.5 with Microsoft PSS and his exchange love never stopped & continued with 2000/2003/2007/2010/2013/2016/2019/O365. At one point in time, he was the only person to support EDS customers when Microsoft had closed all the supports for 5.5 and now for all old legacy Exchange versions.
He used to blog at, manages multiple LinkedIn and Facebook Groups. He also Owns MSExchnageGuru YouTube channel where he uploads all his records technical sessions. Don’t forget to check his PowerShell scripts which are making admins life easier. Prabhat can be reached at

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