In addition to the advice from @Greencat1 there have been a number of users that have not received the update yet but you can manually install the update. Go to this page at MS and either click on Installation Assistant (which is the same as the update) or click on the media creation tool. The tool will create a bootable flash drive and you can install with the option of keeping your files and settings.

Hi there

You may wish to look at the following threads regarding the XPS 7590 and W11 22H2 update

XPS 15 7590, Memory Integrity on causes an inaccessible boot device

https://www.dell.com/community/XPS/XPS-15-7590-Memory-Integrity-on-causes-an-inaccessible-boot/td-p/8273941/page/18

(The Solved flag was done in error as it clearly hasn't been solved)

There is also another thread 

Dell XPS 15 7590; Windows 11 22H2; problems when secure boot is enabled

https://www.dell.com/community/Windows-11/Dell-XPS-15-7590-Windows-11-22H2-problems-when-secure-boot-is/td-p/8283762/page/14

The 2 threads appear to be related to the same issue - they just seem to becoming from different angles and ending at the same critical error inaccessible boot device

Regards

After the latest BIOS update I was able to update to Windows 11 22H2.

Maybe the problem is solved now ;-)

@user_f00a3c​ 

fwiw windows update finally offered me the win 11 update today on my 7590..

makes me thing the niggling bugs have been sort out by microsoft