1. Create a new game for testing so that your current save is left unchanged until you've identified the problem mods/CC.
2. Create some folders on your desktop; perhaps one labeled "Tested Safe Mods-CC", another labeled "Mods-CC Needs Testing" and one more labeled "Broken Mods-CC" so you know which ones to check for updates. This will keep tested mods/CC separated.
3. Exit the game if you haven't already, and divide your mods/CC in half; put one half in the Needs Testing folder and put/keep the other half into the Documents / Electronic Arts / The Sims 4 / Mods folder.
4. Delete the localthumbcache.package file, located in the Documents / Electronic Arts / The Sims 4 folder before opening the game with the half you're testing,
5. If the game works with that half, exit the game, move that half to the Safe Mods-CC folder and move the remaining "Needs Testing" mods back to the Mods folder to test (Again, delete that cache file before opening the game.)
6. Once you know which half is causing the issue, divide those in half, keeping one half in the "Needs Testing" folder and one half in your Mods folder, and test again (delete the cache file each time after moving mods/CC and before opening the game) and moving mods/CC not causing problems into the Safe folder.
7. Repeat this process until you find all that are broken.