Exchange Server 2013 Unable to access OWA or ECP. - "Something went wrong" or "500 unexpected error"

• Open the ADSI editor on the primary domain controller

• Go to CN=Configuration --> CN=Services --> CN=Microsoft Exchange --> CN=

•  Right click CN=Client Access and click properties

• Find the msExchCanaryData0, msExchCanaryData1, msExchCanaryData2 and so on.

• Delete the content of above properties

• Now log onto the CAS server and open IIS management.  Go to application pools and  right click MSExchangeOWAAppPool and click Recycling

•  Reboot the mail servers