Issue installing March 2021 Exchange Server Security Update on Exchange server 2016 KB5000871

Question

Hi After installing the Security update for CU19 (KB5000871) we are getting an error in our Admin portal, after logging in we see the following ECP error in the webportal; “Could not load file or assembly ‘Microsoft.Exchange.Common, Version=15.0.0.0 …”thumbnail image 2 of blog post titled As suggested in https://www.msnoob.com/exchange-ecp-and-owa-error-after-update.html We tried the following things - Change the value in the BinSearchFolders - Checking the Web.Config files for OWA and ECP When we change the value in he BinSearchFolders it does show some content after logging in but the format of the Admin portal is lost. As far as i can see our installation is default apart of the location of the Exchange installation (on D:) Is there anyone who knows how to resolve this? Thanks in advanced, regards Bas

Answer 1

Hi, @Bas Kleian

Did you install the update by double-clicking the update file(run it not as administrator)?
If so, it may be the known issue introduced in the link:
Description of the security update for Microsoft Exchange Server 2019, 2016, and 2013: March 2, 2021 (KB5000871)

Besides editing the values in BinSearchFolders, have you run the UpdateCas.ps1 script under the "\Exchange Server\V15\bin" folder?

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