Hi all
I would like to share my experience about the last update SU10.
Hypothesis:
I bought in 2020 for my retirement MSFS2020 (10 DVD products) and a recent computer with a 3080TI NVidia card with the last update 516.94
I do not have any problem before new installation concerning XBOX , but I can understand that Microsoft wanted to expand the range to others gamers.
I am using since this date a Anti-Virus firewall other than WindowsDefender. (Bitdefender sorry if I name it)
After this last update SU10 installing without problem MSFS2020 refuse to launch.
I am looking for the reasons and try to find solution during 3 days.
During this time I read all you find on internet.
1-Your graphics pilots are not update.
2-Your connexion between MS Store and X Box are not possible.
I tried to restaure Windows Store to Reset an Reinitialize same for XBOX but no result.
On this article I had found some explanation I use
With my Anti-Virus I tried to
DISABLE YOUR SECURITY SOFTWARE
Antivirus and malware checkers can close down or prevent certain applications from launching, even if they are legitimate and safe.
==>But in my case (Bitdefender) it seems that it is impossible to diseable it.
I opened on my second screen my Anti-Virus menu and shown what happen.
If I put off my Firewall ==> Every time I launch the games when the wheel begin to turn the Firewall push again the button to On and the games return to CTD after few seconds
A lot of Error codes as 0X80004005 etc, ypou find it inside Evenement observateurs
So I decided to suppress my Anti-virus definitively and restar my computer.Be carefull
Restart Computer
Others manipulations.
Parameter updater Time and Hour to be sure that all is correct between WStore and XBox
Go into Parameters to Applications
Microsoft Store Repare and Reinitialize you can try one or the two solutions
Xbox console Repare and Reinitialize you can try one or the two solutions
I download XBox Consol a good soft because you can see if you are connected or not to internet and debit to answer to your are not connected
If it is right you do not have problem of internet connection between WStore and XBOX
MicroSoft flight simulator Repare and Reinitialize
Question to community-- Do you know where it is located?? because if you want to put and exclusion where is-it?
My answer after looking for here
C:\Program Files\WindowsApps\Microsoft.FlightSimulator_1.27.21.0_x64__8wekyb3d8bbwe but you do not have the right and I am administrator ??
Stop Windows Defender from blocking** Microsoft Flight Simulator **by adding the launcher to the exclusions list
- Go to Start > Settings > Update & Security > Windows Security > Virus & threat protection.
- Under Virus & threat protection settings, select Manage settings, and then under Exclusions, select Add or remove exclusions.
- Select Add an exclusion, and then select Microsoft Flight Simulator. A folder exclusion will apply to all subfolders within the folder as well.
In that case no Problem to put OFF Windows Defender Real Time Protection Only Off
and also I put and exclusion on the file wherei located Microsoft.FlightSimulator.exe
DISABLE NON-MICROSOFT APPS
3rd party programs such as backup software, tune-up utilities, resources management or even photo/video editing apps can prevent Microsoft Flight Simulator from loading fully.
Stop and restart my computer.
Verification
Xbox console OK excellent internet connection 43ms
MSFS2020 restart and after a few second, I saw my screen windows MSFS2020 where I could begin again the Steps 1 to 5 and it was very quick to obtain MSFS2020 normal.
Sorry for my bad english it is my experience ==>>be carefull I made some copy before reinitialize.
But I do not have uninstall my game and it works normaly, I found all off my controls options.
Only in my case I uses Fsuipc7 I have to add exe.xml file., Content.xml file disspapeared (normal)
Today my question is concerning my anti-Virus I remove I put again or not.
For me BitDefender is a good software but it is not normal when I ask to stop that it continue and I suppose block the sytem.
Last question if some guy from Asobo or Microsft read my post
Why is it impossible to use and oldest update as DCS propose you have a problem you can download the previous update
Why is it impossible to put anther MSFS2020 on a second disk perhaps you can make that with Steam
Which is a good method to install it if you have enough place on a second disk?
Thanks for your experience and feedback 
MANY THANKS TO FS SUPPORT there are a lot of explanation big job 
Have a nice flight if you want other explanation do not hesitate 