Symptoms
Assume that you install the Cumulative Update 3 for Microsoft Exchange Server 2019or Cumulative Update 2 for Exchange Server 2019 in a hybrid environment that has an Edge server installed. When a certificate is configured for the respective send connector, the Set-SendConnector cmdlet doesn't work, and you receive the following error message:
"PowerShell failed to invoke 'Set-SendConnector': Error 0x5 (Access is denied) from cli_GetCertificate"
or
"Error 0x6ba (the RPC server is unavailable) from cli_GetCertificate"
This issue also occurs after you install Cumulative Update 14 for Exchange Server 2016 or Cumulative Update 13 for Exchange Server 2016.
Cause
This issue occurs because the TLS certificate check (in case the TlsCertificateName attribute is populated on the send connector) doesn't work against the Edge servers because the RPC communication is blocked against the Edge servers.
Resolution
To fix this issue, install one of the following updates:
For Exchange Server 2019, install the Cumulative Update 4 for Exchange Server 2019 or a later cumulative update for Exchange Server 2019.
For Exchange Server 2016, install the Cumulative Update 15 for Exchange Server 2016 or a later cumulative update for Exchange Server 2016.
Workaround
The Hybrid Configuration Wizard (HCW) can successfully create the "Outbound to Office 365" send connector if it doesn't exist. This is because the New-SendConnector cmdlet can be used without issues.
Further changes (by using the Set-SendConnector cmdlet) of the "Outbound to Office 365" send connector after the creation aren't possible. However, the "Outbound to Office 365" send connector can be deleted and re-created by using the desired configuration.
References
Learn about the terminology that Microsoft uses to describe software updates.
More information
Microsoft has realized this problem and will post more information in this article when it becomes available.
