Started having this problem this morning. 

The Error Message Appears every single time I try to log in, and it also appears when I click register.

When I click on a page number of a thread in the forums I access through a search engine link, I get the error message.

If I click on certain usernames, my own username included, I get the error message.

I have been able to see the user profiles of EA Users in the forums. Non_EA User Profiles can't be accessed.

Error seems to happen exclusively on the Sims Forum. I have full access to the EA Help Site and the Game Worked fine this morning.

I've cleared the cache of the EA App per the instructions of EA Help, and that did not resolve the issue.

I've tried accessing the forums through Google Chrome and Safari and encountered the same error message. Safari is the Web Browser on my Iphone. Google Chrome and Microsoft Edge are on my PC. Can sorta see things in the forum, coming from a search engine link, but once I'm in the forums, that's when I encounter problems. 

Right Now, I reinstalled the EA App and reinstalled the sims after backing up my saves, mods, and tray. That did not resolve the issue. 

I cleared all of my browsing history, cookies, and everything, and that did not resolve the problem.

I'm probably going to step away and wait until things are resolved, but I wanted to share the things I've encountered while troubleshooting. I hope it helps in some way.