Quick answer: Godot 4 .godot/uid_cache.bin corrupted after rapid editor close/open? Cache not flushed; rebuild via Tools > Rebuild UID Cache.
Quick restart leaves the cache half-written; subsequent loads error.
Rebuild UID cache
Tools menu; one-click rebuild. Cache reconstructed.
Or delete and let regenerate
Delete uid_cache.bin; next editor open regenerates.
Avoid fast restarts
Wait for editor to fully close before reopening. Cache flushes.
“Cache integrity needs clean shutdown. Quick restarts violate.”
If your editor sessions are short, the cache rebuild is your friend. Quick command.