Sims 4 does not start via steam

@Hemfuda  The new user account is a helpful test even if you don't want to accept it as a long-term solution.  If it works, the problem is limited to your main user account; if it doesn't, the problem is global; and either way, you've narrowed down the source.  So please do test it if the following doesn't help.

A few users have said that deleting this data fixes the problem:

https://answers.ea.com/t5/PC/CURRENT-ISSUE-Sims-4-already-running/m-p/13785451#M277450

And that would be an easier fix, so try that first.  You can also try anything else in the first post on page one of that thread that you haven't already covered.

I tried both of the ways you suggested. Zero result.

@Hemfuda  To be clear, deleting the AppData folders didn't help, and the new local admin Windows account didn't help either?  Have you tried everything else in the first post of the "already running" thread?

Please also try setting your computer's clock back to May 25 or so and see whether it makes a difference.  This isn't a solution either, but the fact that it helped a few people is interesting on its own and might shed some light on your particular issue.

And let me know if you get a different error, or no error at all, rather than the "already running" message again.

@puzzlezaddictI deleted EA-App and AppData folders, reset my pc and install EA-App once again - game doesn't starts but the message "game already running" is gone. I created new local admin - still game doesn't start.

I changed clock back - get EA App error message about internet. I turned on Offline mode with changed clock - get EA App error message about internet. I turned off my Internet and tried to launch game on offline mode with changed clock - error message is gone but game still doesn't launch.

I noticed, if delete folder "The sims 4" in Documents and try to run game, it creates only folders "The Sims 4 - Saves" with file "steamcloud" in it. Ok, i reset permissions for Documents - nothing changed at all.

The other things in "workaround" page I did before creating this theme. Also my firewall is also turned off (years ago). I even turned off Steam family sharing because i saw topic with this solution. Still nothing.

P.S. I get "non-steam and EA-App" version of game for test and its works absolute fine.

@Hemfuda  Do you have access to another EA account that owns Sims 4?  If the problem is your account and not your computer, the new account should run the game fine.  Since the base game is free, a friend or family member could add it and let you borrow the account.  (Technically, one person having duplicate accounts are against EA's rules, but....)  Point is, this is a simple test for an issue that might not be on your end at all.

@puzzlezaddictMy games from ONLY EA-App (Sims 2, Dragon age) works fine. But I bought only Sims 4 via steam so I can't check on other EA games that require their launcher.
I get Sims 4 base on my another Steam account and bound it with my second EA-App account game don't want to launch.

I created 3th EA-app account and get base Sims 4 only from Ea-App (no steam or epic) and GAME LAUCNHED! So the problem in Steam+Ea-app games. And I haven't seen any official statements about that. That's ridiculous that i cant play my licensed game FROM STEAM

P.S. All my other games om Steam works fine (that don't require ea-app). Even games from Ubisoft via Steam works absolute fine.

@Hemfuda  Try uninstalling the EA App with Revo Uninstaller (the free version is fine), and restart your computer before reinstalling the App.  Run both Steam and the App as an admin: right-click each desktop shortcut and select "Run as administrator."

If this alone doesn't help, I'd suggest uninstalling Steam with Revo as well; even though other Steam non-EA games work fine, the problem could be something Steam uses specifically to link to EA servers.  The problem here is that by default, uninstalling Steam also removes any Steam-installed games, as the game library is within Steam's program files.  So if you don't want this to happen, create a new game library and move your Steam games there first.

If that would be too much of a hassle, you can try uninstalling Sims 4 with Revo instead, and reinstalling into a different folder just to be thorough.  If you do this, and you still have saves or other user data you want to preserve, rename the Sims 4 folder that data is in (it was previously in Documents > Electronic Arts before you moved/deleted it) so that Revo doesn't flag it for deletion.