After you install and upgrade to Microsoft Exchange Server 2016 Cumulative Update 8 (CU8), you can't access Outlook Web App (OWA) or Exchange Control Panel (ECP), and you receive the following error message:
:-( Something went wrong
We can't get that information right now. Please try again later.
In addition, the following events information is recorded in the Application log of the Exchange server that hosts the mailbox database:
Log Name: Application
Source: MSExchange OAuth
Event ID: 2004
Task Category: Configuration
Unable to find the certificate with thumbprint CertificateValue in the current computer or the certificate is missing private key. The certificate is needed to sign the outgoing token.
Note There is a similar issue, see You can't access OWA or ECP after you install Exchange Server 2016 CU6.