Exchange OWA Error (Something Went Wrong) Exchange 2016 Cu8 on Windows Server 2012 R2 gave error on OWA, ECP will work if administrator doesn’t have a mailbox. else even ecp will throw the same error. An unexpected error occurred and your request couldn't be handled. X-ClientId: 15BED63F62FB4FDB809703ED2534C19D request-id 1ac56275-a1ab-48cf-9f82-880c49767a19 X-OWA-Error Microsoft.Exchange.Diagnostics.ExAssertException X-OWA-Version 15.1.1415.4 X-DAGServer COMM X-DAGerver COMM Date:11/07/2018 3:30:06 PM Description: Unable to find the certificate with thumbprint [Thumb code] in the current computer or the certificate is missing private key. The certificate is needed to sign the outgoing token. or invalid or expired ' Microsoft Exchange Server Auth Certificate' Solution: Create new Microsoft Exchange Server Auth Certificate 1. Open Exchange admin Center ECP, then go to servers, certificates, find Microsof...