I had the same error message but on a completely new PC build and installation. I did speak with EA help so, thought I'd save some of you from having to go through that and write up a post about it lol.
Noticed that every time I tried running The Sims 4, Origin would show in the Friends section that I was "In-game - Playing The Sims 4" even though I wasn't. There was no TS.exe or TS_x64.exe process in the Task Manager. No previous installations of Origin or The Sims 4. Also noticed that occasionally a "new content patch is available" notification would come up in the Origin app whenever I tried to play it and I've have to reload Origin app and/or use "Update Game" option to clear it.
Most are obvious steps. Some I've added as they worked for a friend with a similar issue.
- Repairing Game Files (see My game won't load section)
- Run game without expansion and content packs (Right click on the game in Origin, select Game Properties, you should see a checkbox starting with "Enable <content/expansion pack names>" if you have any installed. Uncheck that and try again)
- Run game in 32 bit mode (Use the Advanced Launch Options to select The Sims 32 bit. Right click on the game in Origin, select Game Properties and then Advanced Launch Options tab. Change the "When launching this game..." dropdown option to The Sims 32 bit.
- Clear Origin Cache
- Clean/Safe Boot PC and uninstall/reinstall Origin
- Create a Local User Account
In my case, it was the last one that did the trick. No issues playing it on a local user account instead of my main, administrator account. Not figured out why yet but I am going to dig deeper.