Game Data Incomplete

Hello, I logged onto my desktop play the Sims 4 today and it gave me the message 'Game Data Incomplete' when I hit play. It told me that the game was referencing neighborhoods that were missing or uninstalled and that If I continued to play I would encounter data that was missing. Yesterday, I logged in and it did not give me this message. Why is is messaging me now? I haven't changed or edited anything on my computer to cause this and even with mods, it would never give me this alert. Is there a way to fix this?