outlook on windows 11 does not connect to the internal exchange error 80000000

Ion Lascu 1 Reputation point
2021-10-21T19:10:40.033+00:00

Hello,
I recently(1 week) switched some of the workstations to windows 11.
But with the transition to Windows 11 I noticed that Outlook Office 365 or Outlook 2016 that I used to connect to the internal exchange server (Exchange server 2010, Windows Server 2008) through Outlook Anywhere no longer works.
The error received is: there is a problem with the proxy server's security certificate. Outlook is unable to connect to the proxy server autodiscover. Error Code 80000000
I mention that the security certificate is a purchased one and that it is functional.
On Windows 10 and Office Outlook 365 or Outlook 2016 works without problems for many years.
I have 3 days of intense internet searches but without success. Everything I tried doesn't work
Please advise me, I don't want to go back to Windows 10 although I reinstalled some more important workstations with Windows 10.

142564-mail-error.png

Outlook | Windows | Classic Outlook for Windows | For business
Exchange | Exchange Server | Management
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8 answers

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  1. Rohan Bradley 16 Reputation points
    2021-11-27T02:28:37.07+00:00

    I was able to solve this issue.
    PLEASE NOTE
    This is not a safe work around
    TLS 1.0 is retired and should be moved away from
    but if you need an immediate resolution do the following

    1. Turn on TLS 1.0 on the local windows 11 system by adding a registry key under
      HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\WinHttp
      DWORD named DefaultSecureProtocols
      with the key value of 00000080
      Save and restart
      Reconnect, the error should be gone and should work offsite

    Other solutions are:
    2) Switch Exchange 2010 to TLS 1.2 (better option)
    3) Switch to newer Exchange or hosted email plaform

    3 people found this answer helpful.

  2. Charles Varvayanis 6 Reputation points
    2021-12-01T10:14:37.84+00:00

    Issue solved by reconfiguring servers:

    Our failed configuration was: Outlook 2013 running on Windows 11 not connecting to Exchange 2010 running on Windows 2008 R2 via proxy.

    Cause of failure: Windows 11 disables TLS 1.0 and TLS 1.1 by default and Exchange 2010 running on Windows 2008 R2 uses TLS 1.0. Therefore, Outlook can't communicate with Exchange. In our case, this happened when the Windows 10 workstations were upgraded to Windows 11 and is only noticed on workstations connected outside of the subnet the server is connected to. That is all of the workstations connected to the same subnet as the server never had a problem after the Windows 11 upgrade, but all of the workstations outside of that subnet failed with proxy (Error Code 80000000).

    NOTE: This is a safe work around:

    Solution: Add TLS 1.2 to the servers. This works because Windows 11 supports TLS 1.2 by default at this time and Windows 2008 R2 can be made to support TLS 1.2. This is great solution because only the server needed to be touched and we did not have to touch the workstations. We followed this for guidance: https://jaapwesselius.com/2018/10/05/exchange-2010-and-tls-1-2/

    Fortunately, in our case Windows and Exchange were already well patched so we only needed to add these registry keys and DWORD items on the server and reboot it.

    Here are all of the registry keys and DWORD items we added:

    <<< TLS 1.2 stuff >>>

    [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols]
    Added Key: TLS 1.2

    [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.2]
    Added Key: Client
    Added Key: Server

    [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.2\Client]
    Added DWORD: DisabledByDefault = 00000000 (0)
    Added DWORD: Enabled = 00000001 (1)

    [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.2\Server]
    Added DWORD: DisabledByDefault = 00000000 (0)
    Added DWORD: Enabled = 00000001 (1)

    <<< TLS 1.2 for .NET Framework 3.5.1 stuff >>>

    [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft.NETFramework]
    Added Key: v2.0.50727

    [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft.NETFramework\v2.0.50727]
    Added DWORD: SystemDefaultTlsVersions = 00000001 (1)

    [HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft.NETFramework]
    Added Key: v2.0.50727

    [HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft.NETFramework\v2.0.50727]
    Added DWORD: SystemDefaultTlsVersions = 00000001 (1)

    1 person found this answer helpful.
    0 comments No comments

  3. Stuart Jeffery 1 Reputation point
    2021-10-22T13:32:01.143+00:00

    I have the same issue. Upgraded to window 11 and just got this proxy error.

    Exchange 2010 with Office 365 Outlook. Works fine in windows 10.

    Want to try windows 11 but can’t if won’t work with Outlook.

    0 comments No comments

  4. P.Souce 1 Reputation point
    2021-10-26T18:57:29.537+00:00

    Had the same issue. Used VPN locally on our network and it worked. But now Outlook only works over VPN.

    0 comments No comments

  5. Tarek Salah 1 Reputation point
    2021-11-07T10:56:53.593+00:00

    I have the same error message with Windows 11 + Office 365 + Exchange Server 2013
    Everything was working with Windows 10
    Any Solution!?

    0 comments No comments

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