Today we are announcing the availability of quarterly servicing cumulative updates (CUs) for Exchange Server 2016 and Exchange Server 2019. These CUs include fixes for customer reported issues as wel...
Updated Mar 18, 2021
Version 4.0
Blog Post
Hi Lukas,
OWA & ECP work after installation.
I've upgraded a second server Exchange 2016 CU19 server (with March 2021 security updates) to CU20:
1. Check: all web.config files are present; \FrontEnd\HttpProxy\<dir>\web.config
2. Upgrade to CU 20 takes a very long time (105 minutes)
3. Event Viewer Application log shows 800 warnings during time of installation:
- Source: ASP.NET 4.0.30319.0
- Event ID: 1310
- Level: Warning
- Event code: 3008
- Event message: A configuration error has occurred
- Exception message: Could not load file or assembly 'Microsoft.Exchange.Clients.Strings, Version=15.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified. (D:\Exchange\FrontEnd\HttpProxy\owa\web.config line 68)
4. Eventually: The Exchange Server setup operation completed successfully.
5. OWA & ECP work after installation
6. Check: all web.config files are present; \FrontEnd\HttpProxy\<dir>\web.config