Symptoms
Assume that you use the New-OWAVirtualDirectory or New-ECPVirtualdirectory cmdlet to re-create the "owa" or "ECP" virtual directory on a Microsoft Exchange Server 2013 or Microsoft Exchange Server 2016 Mailbox server. In this situation, when users try to access Outlook Web App, Outlook on the Web, or the Exchange Administration Center (EAC), they receive an "Http 404" error code.
Cause
This issue occurs because an incorrect authentication method is set for the "owa" and "ECP" virtual directories. When you run the New-OWAVirtualDirectory or New-ECPVirtualdirectory cmdlet to create the "owa" or "ECP" virtual directory, the cmdlet incorrectly enables Forms authentication and Basic authentication instead of Windows authentication.
Workaround
To work around this issue, follow these steps.
For the "owa" virtual directory
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Open Exchange Management Shell (EMS), and then run the following cmdlet to change the authentication method of the "owa" virtual directory to Windows authentication:
set-Owavirtualdirectory -identity "E15MBX\owa (Exchange Back End)" -WindowsAuthentication $True -Basicauthentication $false -Formsauthentication $false
-
Run the following command on both the Client Access and Mailbox servers to restart Internet Information Services (IIS):
iisreset /noforce
For the "ECP" virtual directory
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Start Windows PowerShell.
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Type the following commands, and then press Enter after each line:
Add-PSSnapin *exchange*
Set-EcpVirtualDirectory -Identity "E15MBX\ecp (Exchange Back End)" -WindowsAuthentication $true -FormsAuthentication $false -
Run the following command on both the Client Access and Mailbox servers to restart Internet Information Services (IIS):
iisreset /noforce