Steam - Verify Integrity of Game Files Deletes All Content

Usings Steams ‘Validate File Integrity’ option deletes all simulator content without warning.

Typically when using this option on other games in Steam, it seems to evaluate game files and re-aquires the ones that are damaged. Because this behaves differently for MSFS it catches users off guard on a regular basis.

This is problematic as it forces unsuspecting users to require the simulator content, and may lead to them encountering the Only 2 aircraft bug.

This can be especially upsetting for users who have a slow download speed, or a limited data cap.

Steps to Reproduce

  1. Open Steam Client
  2. Go to the library
  3. Right-click on MSFS
  4. Open Properties, and go to ‘Local Files’ (on left tab navigation)
  5. Click ‘Verify integrity of game files…’

User Expectation:
Clicking this option should analyze the files within the simulator, identify corrupted or problematic files, and replace them.

If this is not possible for some technical reason, this option should either:

  1. Only verify the client files, which are already obtained and updated through Steam.

    • Provide users a facility in the client to verify sim packages from the content manager
  2. Provide a warning to users that clicking the button will “Delete all simulator content. You will be required to download and re-install the simulator when you next use it”

    • If this is not possible due to a Steam limitation, then the button should be disabled. If that is not possible, then option 1 needs to be the option implemented.

I am unable to provide images, screenshots, or videos as my GPU blew up, and I have no access to a computer running MSFS.

I don’t use steam for this sim, but I have seen SO MANY users report getting bit by this issue, I’m gladly upvoting this issue.


This is a Steam function, nothing to do with MSFS. It’s always been like this.

I recommend you post in the Steam forums so the Steam developers can consider it. Voting here will have no effect as it’s nothing to do with ASOBO.


My sympathies.


thanks for creation of an issue… I not run into the trap, but was often reported/mentioned within the forum as a “OMG Why happened” shock effect.

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Can we close this? It’s been documented countless times

I searched bugs and issues looking for a topic but couldn’t find one. If you know of one drop a link below and I’ll be happy to kill this thread.

Guess the OP ask is for a warning to show, but isn’t that a steam ask and not an asobo?


Thanks, I will have a proper look when I get on my laptop.

I have a replacement 30 series arriving tomorrow.

Microsoft/Asobo should have intervened on their Customers behalf a long time ago. I would think that the Microsoft/Asobo team would have a lot of influence. Wouldn’t there be a Contract or Service Level Agreement between Microsoft and a huge distribution partner?

They could ask Steam to remove that option completely. Or change the wording to make it clear what will happen.

This really should be brought up during the next Dev Q&A.


No, non sequitur.

I have just read through that other topic.

No wonder I couldn’t find it when searching, I had looked for topics that mentioned the action ‘verify integrity’ which is not used in the topic once. The Steam button in question has the text ‘Verify Integrity of Game Files’.

Unfortunately, the topic title “The game just erased itself” isn’t overly specific, it doesn’t allude to what the user had done that caused the game to be erased. This is why our team reminds people to use clear and accurate topic titles.

Speaking of which I have updated mine to better reflect the name of the Steam button that caused the issue.

Anyway, I believe my topic has a better description of the issue, including steps to reproduce, an expected outcome and more votes. So I will pass this onto another moderator to make a decision one way or the other (as I don’t believe in moderating my own posts).

While you are right that this is a Steam function, there is something about the way Asobo have implemented their game in the Steam ecosystem that causes this issue.

Out of all my games, I have validated on Steam before, not one has had to be completely re-installed as a result, for affected users, that is the outcome every time they validate MSFS.

Given that, I would argue that it is a bug Asobo should look into. If there is no way for them to prevent it, then I would expect them to lobby Steam. After all, MSFS being on Steams platform makes Valve money, they would have more influence over steam than any small collection of users.


After one day of continuous crashes, i try playing again the game. What i had is a series of crashes even after the starting of the flight (i suppose they were related to game rolling cache and photogrammetry).Then i tried to check the game files via steam version, it will be fast i thought, it is only 1 gb of game files! But nope, the game deleted the entire download of 110gb.

Yes, i have the game on C:, because it is an ssd and it is faster than the mechanical disk, and it seems that the game it is pretty disk-bound.


that really is a strange bug.
So, maybe try to use the Steam “Game File Check”.

I would also check, that there isn´t a problem with your hard drives.

Hard Drive Check

Make sure to report this issue to Zendesk.

Happy landings!

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As i wrote, it is exactly what i did. I see other reports on this forum.

I will check my drive, but you know it’s not the problem.

I will report, this is my third (and definitely most annoying bug), but I payed for the product, and i have even to report the bug to Zendesk. It’s better for them to check this forum, not the opposite, i’m not payed for doing beta testing for them.

Steams only knows about the Core-Game (The files Steam downloaded), which is basically the menu.

Steam is not aware of all the downloaded content within the Game…

So verifying the Game Files via Steam does help nothing (in your case it may even deleted the files)

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The fact that does it know the core game is not a small thing, it is a standard practice to check the files integrity, in certain case it could help.

By the way, now the download is totally stuck to the file “fs-base-cgl-0.1.21.fspackage.001”. I can’t even find it for deleting and attempting a re-download.

had the same thing (like many other users) while downloading the last patch.
Only thing that helped (for me) was using netlimiter and limit the download-bandwith of flight simulator.
After limiting the bandwith I had no more file-downloading-loops.

(all other ‘solutions’ found in the web, did not help ME).

This is a known bug. If you run Steam check files, it deletes the files. Did that to me. Fortunately, I am meticulous about backing up.

Never did ‘check files integrity’ of Steam help anything (for me)… I never had problems with game files. 99.99% of the time it’s not faulty game files, it’s a faulty configuration somewhere.

So I’d say, there is almost never a reason to run the check integrity feature of steam. The risk that is messes something up is higher than the chance it does help.