Several days ago I tried to start msfs2020, just like I’ve been doing for years, and I got this error dialog:
This app can’t open. Microsoft Flight Simulator can’t open because it is offline. The storage device might be missing or disconnected.
That storage device is online…I can run apps from it. My pc isn’t offline…in fact, I’m online right now typing this! 
I’ve opened a ticket with zendesk, they suggest to reset the store app, uninstall/reinstall Microsoft Gaming Services, etc. I’ve done all they suggest, yet still can’t open msfs2020.
There are three other posts here with this topic, and none of the fixes in them work for me either.
Any hints from the experts here?
Thanks!
Well…it seems all I needed to do was create this post and then the answer revealed itself!
I went to my windows Start Menu - Settings - apps & features - microsoft flight simulator - advanced options - repair
And now the sim is working again.
I swear I did that yesterday and it didn’t fix it, but…this time it did. Whew!
Well, 2024 borked my 2020 install again. This time, a simple repair didn’t work. Here’s what worked:
- Uninstalled 2024
- Installed 2020 from store to f:\xboxgames. It’s always been installed in e:\msfs2020, but when I’d point the install there it’d complain about not enough disk space. I finally gave in and pointed it to f:.
- It downloaded 2Gb, then spent a while at “checking dependencies”.
- Did it end up in e:\msfs2020 anyway? Sure looks like it. ???
- While the store was still checking dependencies I decided to try starting 2020. It started!
- Installation manager came up, I need a 43mb update, to e:\msfs2020, so yep…it fixed the original install location. Sweet!
- Store finally stopped checking dependencies, 2020 started fine.
With the new 4070 super I bought for 2024, I’m now running 2020 at 1080p in ultra at 40fps, rather than medium/high custom settings at 21fps that I was running it at with my 1660TI for the last 4 years…looks stunning!!
Not gonna lie…2024 may not get reinstalled for a while.