Hello,
I am Rubiat. I have two mailbox server which is running on Exchange Server 2016 CU21. Last night I installed security update KB5007409 in one mailbox server. I bring this on maintenance mode and then installed this update via command prompt. In the installation process all of the Microsoft Exchange service was disable state. I revert back from maintenance mode after installation was successfully done. I restart my server and then I ran all the services manually. I connect exchange management shell but It couldn't connect because world wide web service is disabled. Then I ran the world wide service and after that I can connect management shell. But the problem is that when I was trying to connect ECP & OWA, I got Error 500 in the case of ECP and OWA was loading state. That moment some of my users couldn't connect in OWA. Then, I removed the autodiscover and webmail entry from my local DNS and problematic Mailbox Server takes offline from Reverse Proxy, they can connect OWA. Some hours later I restart that problematic server again and try to connect ECP & OWA with localhost, I can connect it easily. Then I again give the autodiscover and webmail entry on my local DNS and take the server online in reverse proxy, I can not connect ECP & OWA again. When I put my username and password in ECP & OWA login page, it can not provide access me to my mailbox and control panel rather it redirect me the same login page again. Then again I removed DNS entries and bring this server offline in Reverse Proxy, I can easily connect again. I attempted to uninstall the patch from that mailbox server but it couldn't uninstalled. I got a prompt when I try to uninstall it. Now, please tell me how to fix it. It is become a big issue now. I have only one mailbox server now and I have 4K+ users. So, please provide me a suggestion as soon as possible. Thank you.
