Before diving into the specific patches for version 10.8.1, it is essential to understand the nomenclature used by Esri. Navigating the download centers and support articles can be confusing if you cannot differentiate between the types of releases.
Patches are reversible (via Windows Control Panel or Linux rollback scripts), but a botched patch can leave your services offline. Follow this checklist : arcgis server 10.8.1 patches
Each patch has a containing:
Operating systems evolve. Windows Server and Linux distributions receive their own updates. Occasionally, an OS update can conflict with the GIS software, causing services to crash or fail to start. Esri releases patches to maintain certification with newer OS versions. If your IT department plans a server OS upgrade, you must verify if your current ArcGIS Server patch level supports the new OS build. Before diving into the specific patches for version 10