can not lauch BF4

Thank you for the additional information! As I mentioned before, but to reiterate:

"Cause: Account data is not properly synced between the Origin version and the current EA app. This is most likely the cause of the problem." As this is a backend server-side issue, we, as forum volunteers, cannot intervene or fix it further. As a last resort, please contact EA Help directly and ask them to unlock and reset your account sync flag.

3) "An error occurs when someone joins the server while you are playing alone."

This is wrong, there is no error occured other players joined while I was playing alone. 

And I can join a server which has players as a spectator but a soldier or commander. It's just like Trump, Putin and Xi  all the three presidents hate me, don't allow me to become their courtries' soldiers. 😂😅

Some players have the same issue:

BF4 - Error - An error was reported from EA Online | EA Forums - 13396652  like this guy

https://tieba.baidu.com/p/9889815378  On 2025-07-21

https://tieba.baidu.com/p/10474579348  On 2026-02-09 this guy had problem https://tieba.baidu.com/p/10502863827 On 2026-02-21 he can play again.

What can I do to solve it then?

Thank you for the detailed information. First, 1) "You can join servers with no players," 2) "You cannot join if there is even one player," and 3) "An error occurs when someone joins the server while you are playing alone." In other words, "Your account is not synchronized." This is not a game software issue. The fact that you can actually join the server is proof of that.

Cause: The account is not properly synced between the data from the Origin version and the current EA app. This is likely causing the issue.

The last time I logged into Origin should be a few years before it shut down. 

I can still play BF4 normally in April. Then in earlier May, I found that I can not play, there is nothing I changed this time. 

Please notice, nowadays I can still join in an empty server.😂 It seems that a problem I connect to a server with players.

You could try reinstalling the game.

Hello. Have you previously accessed BF4 through Origin? Are you currently launching the game from the EA app or another store (such as Steam)?
If you previously played via Origin, your account information may not be synced with the current EA app/Steam system.

Just re-scaned the game files, soon I found it seems that not the user end's problem, as I found some users had the same issue. Like an other post from here.

Also not the account's problem, as I can join in an empty BF4 server only.

I don't know what's the matter with the trash EA online......the issue has lasted for 2 weeks. Now I am playing BFH instead of BF4.

Hello ButinKimXi​,

What troubleshooting steps have you tried to resolve the issue?

  That's the way I came here. I searched that yesterday, and found one guy had the same issue five days ago, haha.😀😃😄😁