SourceOne: Web Search message open and download fail

After Installing or upgrading to SourceOne Email Management 7.2 SP9:
Messages cannot be opened or downloaded (Email/File) from a web search portal. Double-clicking the email or by clicking the file name results in no apparent action.

The following error might be reported in the browser or in the browser dev tools network traffic logs:

Server Error in '/Search' Application.
The resource cannot be found.
Description: HTTP 404. The resource you are looking for (or one of its dependencies) could have been removed, had its name changed, or is temporarily unavailable.  Please review the following URL and make sure that it is spelled correctly.

Requested URL: /Search/Download.aspx

A fix for this issue is to be included in full installation packages (service packs) higher than 7.2 SP9.
To resolve this issue in affected versions of SourceOne 7.2 SP9 change the Search application pool-managed pipeline to classic by performing the following:

1. Open IIS Manager and navigate to application pools.
2. Locate the Search application pool and see that the Managed Pipeline is set to Integrated.
3. Right click Search and select Basic Settings.
4. Change the Managed pipeline mode to Classic using the drop-down menu and press OK.
5. The application pool should automatically restart but if it does not recycle it manually.
6. Test Search open/download to confirm the issue is resolved.