Sophos for Microsoft SharePoint: error 'Exclusions could not be applied'

Issue
During installation or removal of Sophos for Microsoft SharePoint, an error message is displayed:

Setup was unable to add [remove] exclusions folders to [from] Sophos Anti-Virus. Setup will now proceed but please contact technical support for information on how to perform this operation manually

Typically this issue appears on an Enterprise Console-managed system. Sophos Anti-Virus Exclusions might fail to be configured on a managed system.

Sophos Product and Version
Sophos for Microsoft SharePoint

What to Do

• If your computers are managed by enterprise console:

You must manually update the exclusions following installation or removal of Sophos for Microsoft SharePoint.

• If your computers are not managed by enterprise console, you must manually update your exclusions in Sophos Anti-Virus:

1. Open Sophos Anti-Virus, select Configure|On-access scanning|Exclusions
2. Exclude the folder 'C:\Program Files\Sophos\Sophos for Microsoft SharePoint\Temp' (if you installed the product in the default location).
3. Open Sophos Anti-Virus, select Configure|On-demand extensions and exclusions|Exclusions
4. Exclude the folder 'C:\Program Files\Sophos\Sophos for Microsoft SharePoint\Temp' (if you installed the product in the default location).