@gkensington
This sounds like it may be caused by outdated or recently deleted mods or custom content.
If you haven't already, try moving your mods folder to the desktop, clear your game cache and delete the localthumbcache.package from the Sims 4 folder to help with troubleshooting.
Try playing the game again to test. If it loads okay, it may be that some of the mods/cc have become outdated.
How to Delete Cache Files
https://sims4.crinrict.com/en/2014/09/delete-cache-files/
Custom content can become outdated with most new game patches. If the game works when the Mods folder is removed, then one or more of the mods and/or custom content has become outdated and will need to be removed or replaced. EA/Maxis aren't responsible for broken mods/cc. It's up to the creators to fix.
Disabling or turning off both mod/cc options isn't enough of a test.
Try the 50/50 method:
1. Move all the mods and cc out into a temporary folder on the desktop.
2. Move a few files back at a time. Load the game to make sure it loads and everything is good.
3. Delete the localthumbcache.package from the Sims 4 folder.
4. Repeat steps 1 - 3 till there is no more files to check.
** While your testing, don't save the game. If you find any problems, delete the mod or custom content file.
How To Find Problem Mods and CC
http://simswiki.info/wiki.php?title=Game_Help:TS4_Finding_Problem_Custom_Content
