Windows 2019 has been released by Microsoft and is now Generally Available for SAP NetWeaver 7.0 or higher components.
Release information can be found in 2751450 - SAP Systems on Windows Server 2019 https://launchpad.support.sap.com/#/notes/2751450
Most common SAP applications are now Generally Available on Windows 2019.
Windows Operating System support is generally dependent on the SAP Kernel for ABAP system or JVM for Java Systems; SAP Support Packs usually do not need to be applied. Most SAP applications that support ABAP Kernel 7.22 or 7.53 (or higher) or JVM 6 (or higher).
The SAP Product Availability Matrix contains the required release and support information. As of March 2019 not all DBMS are certified on Windows 2019. SQL Server 2012 (or higher), Hana 2.0 client libraries and LiveCache are supported. DB2 LUW, Sybase and Oracle databases will be certified in due course
Check the SAP Product Availability Matrix for the supported SAP Application and Database combinations. https://support.sap.com/pam
1. Windows 2019 is Fully GA on Azure
Windows 2019 includes many features deeply integrated into the Azure public cloud platform. SAP on Windows 2019 is simultaneously released for on-premises deployments and on Azure cloud deployments. The full list of Operating Systems and VM types supported on Azure is documented in SAP Note 1928533 - SAP Applications on Azure: Supported Products and Azure VM types https://launchpad.support.sap.com/#/notes/1928533
2. Azure Site Recovery Support
Azure Site Recovery fully supports Windows 2019 for the Azure-to-Azure scenario. Customers can protect SAP Applications server VMs using Azure Site Recovery
https://docs.microsoft.com/en-us/azure/site-recovery/azure-to-azure-support-matrix
Documentation for Protecting SAP workloads with Azure Site Recovery https://docs.microsoft.com/en-us/azure/site-recovery/site-recovery-sap
3. Hyper-V 2019 Support
Windows Server Hyper-V 2019 is already Generally Available and supported. A Hyper-V 2019 host can contain Windows 2019, Windows 2016, Windows 2012 or Windows 2008 (R2) guests. Review SAP Note
1409608 - Virtualization on Windows. https://launchpad.support.sap.com/#/notes/1409608
4. What’s New in Windows 2019 for SAP
Windows 2019 provides several new features and multiple enhanced and improved features for SAP Customers. A summary of new features can be found here: https://docs.microsoft.com/en-us/windows-server/get-started-19/whats-new-19
Windows Admin Center https://docs.microsoft.com/en-us/windows-server/manage/windows-admin-center/understand/faq
Windows Clustering includes a new feature useful for SAP customers called Azure-aware clusters. Windows 2019 cluster can receive and respond to Azure planned maintenance notifications. Windows cluster will failover services before planned maintenance events occur
https://docs.microsoft.com/en-us/windows-server/failover-clustering/whats-new-in-failover-clustering
Windows 2019 and Windows 2016 support in-place OS upgrades of an ASCS Cluster. The minimum source release for the cluster is Windows 2012. The following note also applies to Windows 2019 2419847 - Support of Windows in-place upgrade in Failover Cluster environments https://launchpad.support.sap.com/#/notes/2419847
5. Windows 2008 (R2) is End of Life – Plan Migration
Customers running on Windows 2008 or Windows 2008 R2 should immediately start planning to upgrade to Windows 2019. Customers running on old Java Applications (such as Enterprise Portal 7.0x) version 4 or 5 JVMs (not supported on modern OS versions) should start reviewing the different upgrade paths available.
2749767 - Support of SAP Products on Windows Server 2008 (R2) after January 2020 https://launchpad.support.sap.com/#/notes/0002749767
1494740 - SAP System Migration from Older Windows Releases to Newer Ones https://launchpad.support.sap.com/#/notes/1494740
https://support.microsoft.com/en-us/lifecycle/search?alpha=windows%20server%202008
Additional Links & Notes
2749767 - Support of SAP Products on Windows Server 2008 (R2) after January 2020 https://launchpad.support.sap.com/#/notes/0002749767
2734697 - Windows Support for SAP Kernel 7.73 https://launchpad.support.sap.com/#/notes/0002734697
2770441 - HANA client installation fails with: Cannot determine system32 path - Cannot find system directory inside windows registry https://launchpad.support.sap.com/#/notes/0002770441
Microsoft Product Lifecycle Support tool https://support.microsoft.com/en-us/lifecycle/search?alpha=windows%20server%202008
SAP’s Windows Blog https://wiki.scn.sap.com/wiki/display/ATopics/Frequently+Asked+Questions%3A+SAP+on+Windows+Servers
https://wiki.scn.sap.com/wiki/display/ATopics/SAP+on+Windows
https://blogs.sap.com/2019/03/15/sap-support-for-windows-server-2019/