Game wont start

Bug Reporting Hub Crashes (CTDs)
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17

The “request not supported” is a bit different than the main topic. Some infos about in forum:
: Search results for 'request not supported ' - Microsoft Flight Simulator Forums

As example here a user reported " Cannot start Microsoft Flight Simulator ('The request is not supported' pop-up error) - #4 by DressierCone45 starting as admin" will help. Sounds a bit strange and may be its not the same as I understood you done a clean re-install.

I remember for an very old case where usere reported a windows update caused this, which sounds like your report. If realy nothing will help, you can show us the windows update history and you can may be try to rollback the update.

I have another case in mind, but… cant find for the moment…

EDIT: ah… sorry… I read your post wrong. You try to do a clean re-install. Have you done the former “uninstall” accordently to these steps ?

https://flightsimulator.zendesk.com/hc/en-us/articles/360016107019-How-to-repair-or-remove-and-do-a-clean-install-of-Microsoft-Flight-Simulator-on-Microsoft-Store

Important might be the clean up of folders. May be there are some files left which cause that.