ERROR: could not locate data files. Please reinstall FINAL FANTASY XIV.(50000)

[Moonraker]

Games been fine until yesterday during maintenance (data center change in EU)

Logging to Windows shortcuts were broken and Steam on launch gave this erro:

Steam Error - "Failed to launch game (missing executable)

Checking it appeared that for some reason it had wiped all the FFXIV files and kept trying to download a new install.

No problem as I had backed up the 'FINAL FANTASY XIV - A Realm Reborn' folder from Steam to an external HD so added it back to the Steam Steamapps common folder. Usually this prompts a file check on launch in Steam with other games. This time it just kept trying to start a new install.

I tried trashing the Steam appcache which did not help. All the time I was able to launch FFXIV via the ffxivboot.exe to Launcher no problem. Could not connect because of data centers down but working as expected, just not via Steam.

After trying several times a couple ot checked existing files but still started downloading the FFXIV Install again.

Eventually I decided to use a Restore Point in Windows 10. On reboot all the shortcuts were as before and I was able to launch as normal via Steam. So waited until today to launch and play.

However, after the Launcher launched and checked FFXIV etc. on pressing the Green button it now gives this error:

could not locate data files. Please reinstall FINAL FANTASY XIV.(50000)

Tried rebooting and still the same. Tried removing the MyGames > FINAL FANTASY XIV - A Realm Reborn folder. Reentered login details but then got a message about suspicious activity.

Had to then reset password which worked. However after trying all this I still am getting this message each time pressing the green play button on the launcher;

could not locate data files. Please reinstall FINAL FANTASY XIV.(50000)

Now at a lose about what to try. My broadband is limited so it's a 16 hour redownload which I would prefer to avoid is possible if it could be something else.

Anything else worth trying or suggestions?

[Moonraker]

Solved: Apparently Steam had wiped out all the data in the Steam > Steam Apps > common > FINAL FANTASY XIV - A Realm Reborn yet again for no reason.

Installing backup folder fixed the issue. No idea why Steam is resetting the data especially as I don't believe that there was a version change just new data center?