When you log in the Exchange Admin Center or Outlook on the web (Outlook Web App) in Microsoft Exchange Server 2016 or Exchange Server 2013, you get a blank page. When this issue occurs, event ID 15021 may be logged.
This issue occurs if the SSL binding on 0.0.0.0:444 has one of more of the following issues:
The binding is installed incorrectly
The binding doesn’t have a certificate assigned.
The binding contains incorrect information.
For example, this issue occurs if the certificate hash of the binding is different from that of other bindings for application ID 4dc3e181-e14b-4a21-b022-59fc669b0914.
Resolution for Exchange Server 2013
To resolve this issue, install the following cumulative update:
2961810 Cumulative Update 6 for Exchange Server 2013
On the CAS server, open Internet Information Services (IIS).
Expand Sites, click Default Web Site, and then click Bindings on the Actions pane.
In the Site Bindings dialog box, open the binding for https on IP address * and port 443.
Verify that a valid SSL certificate is specified for the site. If not, specify a valid SSL certificate, for example the Microsoft Exchange certificate, and restart the IIS service by running the following command in the command-prompt window:
On the mailbox server, do the same verification for the Exchange Back End site.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.