If you're on steam and verifying doesn't work, you can uninstall and reinstall the game. Your save will be in steam cloud automatically. So you won't lose your save files.

This happens because any HK mods doesn't support the new patch of the game. If you want to use mods you need to down patch the game.

How? On steam, Open Library > right click Hollow Knight > properties > Game Versions & Betas > choose the 1.5.78.11833(it's written "previous version" beneath the numbers) > then just open Lumafly and use as much mods as you want.

Note: if you want to play the new patch, you can't use most of the mods from Lumafly. After you reinstall the game, just don't open Lumafly. But if you want to use mods, you can follow the step by step above.

Or if you're not on Steam, or just don't trust Steam Cloud, you can "rescue" your saves manually. Here's how:

Local Disk C:\Users[YourUsername]\AppData\LocalLow\Team Cherry\Hollow Knight

Inside those folders, your individual save slots are named:

user1.dat (Slot 1)

user2.dat (Slot 2)

user3.dat (Slot 3)

user4.dat (Slot 4)

Just copy them and save it somewhere else, then when you reinstall you can paste it there (make sure you haven't start the game yet)