ArcGIS Maps for SharePoint 5.1.1 fails to install on a Microsoft SharePoint 2016 farm after Microsoft security update KB 4484336 is applied

Description

After applying the latest update to SharePoint 2016, ArcGIS Maps for SharePoint setup throws the following error and crashes:

“Cannot load assembly Microsoft.SharePoint”

This issue affects SharePoint 2016. SharePoint 2013 and SharePoint 2019 are not affected

Cause

This is a known issue, BUG-000131436. Starting with Cumulative Update KB4484336 for SharePoint 2016, the Microsoft.SharePoint.dll can no longer be dynamically loaded from its location within the Microsoft.NET Assembly Cache by the ArcGIS Maps for SharePoint Setup.

This issue only affects the Setup.exe process. After applying the below resolution, the issue can be safely ignored.  There are no runtime implications of this issue.

Workaround

1. Copy the following .dll into the folder containing the ArcGIS Maps for SharePoint 2016 Setup.exe and then execute.

%windir%\Microsoft.NET\assembly\GAC_MSIL\Microsoft.SharePoint\v4.0_16.0.0.0__71e9bce111e9429c\Microsoft.SharePoint.dll

2. Execute the ArcGIS Maps for SharePoint 2016 Setup.exe, the Setup will now be able to load the Microsoft.SharePoint.dll assembly and proceed normally.