Update 7/15/2025: Added a mention of Exchange 2016/2019 ESU program.
In May 2024, we shared our Exchange Server Roadmap Update and our plans for the future of Exchange Server. Since then, we’ve bee...
Updated Aug 13, 2025
Version 17.0
Blog Post
I upgraded my Exchange Server 2019 CU15 running on Windows Server 2022 to Exchange Server Subscription Edition and it said that the operation completed successfully. My event logs are full of warnings and errors. Exchange services arent starting.
The system log shows events like below for each application pool that I have.
Log Name: System
Source: Microsoft-Windows-WAS
Date: 10/1/2025 1:49:31 PM
Event ID: 5139
Task Category: None
Level: Warning
Keywords: Classic
User: N/A
Computer: FvMAIL19
Description:
A listener channel for protocol 'http' in worker process '13220' serving application pool 'MSExchangeOWAAppPool' reported a listener channel failure. The data field contains the error number.
The application log is showing error events like below:
Log Name: Application
Source: Microsoft-Windows-IIS-W3SVC-WP
Date: 10/1/2025 1:54:43 PM
Event ID: 2280
Task Category: None
Level: Error
Keywords: Classic
User: N/A
Computer: FvMAIL19
Description:
The Module DLL C:\Program Files\Microsoft\Exchange Server\V15\Bin\kerbauth.dll failed to load. The data is the error.
I did not have these events prior to the upgrade. Any ideas on how to address this?
Thanks