bdary
Bobmitch
I got the 24H2 update on my desktop yesterday. Ran the upgrade and all seems pretty stable.
Windows 11 Pro 24H2 26100.1882) 
Still waiting to see it appear as an update on my rig yet.
I got impatient tried to update using the "Installation Assistant" on my rigs. My Z370 Classy/9900k/3090 FTW3 Ultra worked without a hitch but my Z690 Hero/12900k/ASUS 4090 TUF OC stalls in the secondary phase at 86% and rolled back successfully (multiple times). This also happened using the 24H2 ISO with just the LAN and keyboard/mouse connected (same 86% stall) and how I got the error message below. Tried all the usual suspects/fixes but everything seems to point to a driver issue, and I have everything up to date. Will just wait for the dust to settle and hopefully it'll turn up in Windows Update sometime soon.
0C1900101 - 0x4000D
The installation failed in the SECOND_BOOT phase with an error during MIGRATE_DATA operation. EDIT: Finally solved the installation problem on my main rig - Turned out to be Norton 360. Nice to see the install progress past 86% to 100% after so many attempts. I nuked it with the Norton supplied tool and performed an upgrade to 24H2 using a virtual mounted ISO. Must have tried everything under the sun before doing what I should have done as a first step troubleshoot! Strange how my second rig that was also running a license for Norton 360 went through without a hitch.