* Be sure the version in your environment and the version of the Hotfix are the same

(the first three numbers should match)

For example, the hotfix 3.4.0-HF1 can be installed if the server is running version 3.4.0. or 

the hotfix 3.4.0-HF2 can be installed if the server is running version 3.4.0-HF1 or

But the hotfix 3.4.1-HF5 cannot be installed if the server is running version 3.4.0-HF2.

* Download and extract the ZIP file from the link you received 

* Stop M&D Service

* Create a backup of the M&D folder

* Copy the extracted files to the root folder of M&D (press replace)

* Start M&D Service

* If using M&D Extensions for Qlik Sense. In Qlik Sense QMC -> Extensions

       - Delete MailAndDeploy Extensions

       - Import MailAndDeploy Extensions from "C:\Mail & Deploy\SelfService\Qlik Sense\"

       - Hard Refresh the browser with the App using the extensions