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After installing the various Hafnium updates I am no longer able to access ECP (HTTP Error 503) of Exchange 2016. I've reset the SSL certificate, changed the SSL certificate and removed and re-added the ECP folder via PowerShell. Nothing helps or seems to make any difference. OWA works fine.
Turns out the MSExchangeECPAppPool had been stopped after the update and even after a reboot. Should have checked that earlier, but assumed it would be started after a reboot.
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Hi @Richard T ,
Great to see that you;ve figured it out and thanks for your sharing! You could click "Accept Answer" under your own post to close this up. This can make answer searching easier for others who encounter a similar situation. Thanks!
Have a good one :)
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