Information: Internal caches are corrupted or have outdated format, forcing project rebuild: backward reference index should be updated to actual version

So IDE gives me this message, ending in "should be updated". It is absolutely not clear what it means: whether it's me who should take an action to update indexes and caches, or IDE will take care of it.

If former, it would help to describe what actions user actually should perform. If latter, why am I seeing this at all?