Unable to send out client event notifications

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Client event notifications are not sent out and an error message appears.


The following error is logged when the issue occurs:

"Error","MessageBus","61012","ConnectionError","ExchangeWebServicesOrigin","61012 Exception from message source xxx@yyy.com: System.Net.WebException: The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel. ---> System.Security.Authentication.AuthenticationException: The remote certificate is invalid according to the validation procedure.

Troubleshooting Steps

These steps are applicable to K2 environments integrated with Exchange On-Premise.
  1. Open the Connection String Editor in [\K2 blackpearl\Host Server\Bin]:

  2. Choose any of the EWS Exchange connection strings on the left panel: 

  3. On the right panel, copy the value of the URL Connection String Property:

  4. Open this URL on the browser and ensure that there are no certificate errors or warnings:

  5. If any errors appear, please raise this with your Exchange Server admin.