How to fix EA app Error 500?

The update to the EA client is problematic for a lot of people for a bunch of their games. Solution is to re-install the Origin client and apply a fix to it. After having installed the EA client, it uninstalls the original Origin client. But, you can get the last good working Origin client installer on TechSpot;
https://www.techspot.com/downloads/5783-origin.html

Keep the EA client app as it's needed for verification in some games. But, you'll want to change some of it's settings. Disable 'start with Windos. Change game install directory to the Origin clients game install directory... \Orign Games. Link steam if you have games bought through Steam for EA/Origin client. Restart PC after all this so all these changes are saved in Windows Registry.

Now install the Origin client, log in....it'll self update and softlock due to that stupid EA client notice. That's ok. Close out Origin client. Run task manager and kill the Origin web helper service.....it keeps running in background. Now open file explorer and change view settings to 'show hidden system files and folders.'

In the C: drive, you should now see a folder called "Program Data." Open it and go to the Origin folder.......

Stop origin client loading EA app message;

1. Open C:\ProgramData\Origin\local.xml in notepad
2. Add new key there:

<Setting key="MigrationDisabled" type="1" value="true" />

This should go at bottom just above the last line which is "</Settings>."
Save the file and exit. Now launch Origin and that stupid notice will be gone. Exit and Restart your PC again to finalize settings.

Congrats...you should be able to play your games properly now.

If a game is not working correctly, click it in Origin client library, click the gear icon and select 'Repair.' If it still doesn't seem to work, try uninstalling and re-installing.

If it's a game bought through steam, you'll install it using steam. Then launch Origin client, select that game in the library.... it'll show a 'download' button still. Click it, Origin will find the steam install and change the button to 'Play.' Always play your games using the Origin Client and the 'play' button for that game in the Origin client library. Some games will work properly using the desktop shortcut but, others will try an launch the EA client.....which we know can be problematic for some games. Still, some games maybe throw errors if you don't have the EA client background task running so, for those, run the EA client, minimize it, then use the Origin client to launch the game.

Special thanks go out to user @tom_looken for pointing me to the code line for fixing Origin client.

500 error in worthless app.  We need alternate options to launch games we purchased!  This doesn't bode well for longevity of games,  if you guys have complete control.  I purchased a game,  I didn't rent a game for as long as you keep it alive!  Long existing account,  uninstalled,  cleared cash,  have done it all,  multiple times.  I shouldn't have to reinstall the app daily!  I shouldn't have to do anything but launch the game.  I shouldn't have to clear cache,  and reinstall games again! 

This app was forced down our throats. We did not ask for it. EA gave it to us. My games were working well under the Origin app. So why did EA change from Origin to a app where we have to wait for EA's permission to play games that we bought? Hey EA! Can I play my Sims 4 game if it's o.k with you? And don't expect me to buy any more games from you. I don't loke throwing my hard earned money away on garbage.