Drag drop files here option missing for SharePoint document library

Microsot's collaboration platform "SharePoint" gives you a handy feature for bulk uploads, "Drag and Drop". This feature is available with both SharePoint Online and SharePoint on-premise versions (2010, 2013, 2016, 2019).
You can easily move files and folders by simply dragging and dropping to the SharePoint Document Library from Windows Explorer.

But did you come across a case where the "drag files here" option is missing for the SharePoint document library? If yes, then let's understand the problem and learn how to fix it.

Why drag and drop is missing in the SharePoint library?

SharePoint Online - The "drag files here" feature of SharePoint Online works with HTML5 and requires software that supports HTML5, the browser. So this should work with most of the latest browsers like Internet Explorer, EDGE, Chrome, Firefox, Safari.

SharePoint 2010/2013 - The "drag files and folders here" feature of Sharepoint 2010 and 2013 requires an ActiveX control named "STSupld.UploadCtl", which should be an updated version.

How to fix missing drag and drop in SharePoint library?

SharePoint Online - As this requires a browser with HTML5 support, install the latest version of the web browser. Or install Microsoft Office 2013 or SharePoint Designer 2013.
When Office 2013 or SharePoint Designer 2013 is installed on the client computer, it installs the SharePoint Drag/Upload Control.

SharePoint 2013 - Enable ActiveX Control STSUpld.UploadCtl via manage add-ons.
This depends on Microsoft Office 2013 feature, C:\Program Files (x86)\Microsoft Office\Office15\STSUPLD.DLL

SharePoint 2010 - Enable ActiveX Control STSUpld.UploadCtl via manage add-ons.
This depends on Microsoft Office 2010 feature, C:\Program Files (x86)\Microsoft Office\Office14\STSUPLD.DLL

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