I started having this problem today.
The game crashed, and when I opened Sims 4 next, I had an error message popping up in the right top corner. Sims Delivery Express Connection Error. When I try to open the game I was playing when it crashed, I'm notified that the game has items placed in world that I don't have downloaded via Sims Delivery Express. Clearly I once had said items. I don't know where to look to see if I still have said items (I wouldn't even know which items were missing if I were to load a different game).
I don't have any EP/GP/SP/Ks. I removed the mods I had, and still had the same problem.
I have restarted the game multiple times along with my computer.
I went into the Game Options menu on the Sims Delivery tab and attempted to check for updates. On that tab, it has a big message saying that the download stopped with a button to "resume download". Every time I click the button, it attempts to connect to check for updates for a second and then stops. My computer is connected to my home network which has active internet connection. I do have a VPN, but I have tried this with VPN both on and off.
I had no indication of what caused the crash. No error message after, either. Just a clean, sudden software ended.
In the bug report for the Delivery Express connection error mentioned above, I read that removing the "content" folder in your "documents" would prompt the Delivery Express stuff to redownload. I don't have a "content" folder in my "documents" folder, nor in "documents > electronic arts > the sims 4".
I have Windows 10. I don't play Sims 4 every day, but I have played before today and since I last installed any updates for OS or anything else. Nothing has changed to my knowledge between when I last played Sims 4 and when the crash happened.
---
I'm sorry you've had this problem for so long. I imagine it's very annoying. I will link that other bug report. The two errors may be related to one problem with the Delivery Express system.
@KeeperShadyL Here's that other bug report:
https://answers.ea.com/t5/Bug-Reports/Sims-Delivery-Error-Code-00000008-0000000000000000/td-p/11043740
(CM: Multiple posts merged. Check out this post for tips on how to edit and add more to a post.)