Microsoft Windows Cumulative Update Previews available today April 26

  At times Microsoft will release Windows cumulative previews to the public as a preview for Microsoft Patch Tuesday due May 10.

 Windows 10 has cumulative update

KB5011831

 Windows 11 has cumulative update

KB5012643

Both update previews have more detail by viewing the Knowledge Base (KB) article on the Microsoft site.

NOTE: This cumulative update preview is reported to cause some problems/issues:

Safe Mode may cause screen flicker - Safe Mode without Networking.

Some also report very long boot times.

Microsoft has addressed this via known issue Rollback.

This should be addressed by the May 10 Microsoft  Patch Tuesday.

UPDATE: Release today (May 2) Cumulative Update Preview for .NET Framework 3.5 and 4.8 for Windows 11 x64