What is the cause of this error "Leaked at exit"

[xyprohero20]

Godot Version

sometimes it display this error upon exit sometimes not idk why. is this should be worry or not. Thanks in advance !!

Question

[herrspaten]

I think this refers to memory leaks. That means that there where nodes existent in memory, but no more existing reference to them, making it impossible to access them

[smix8]

RID leaks are when a server could or did not delete them before the game had the shutdown and the engine closed.

In this case whatever script, addon or extension uses PhysicsServer.create_xyz() to create physics RIDs does not call PhysicsServer.free_rid() for them before the game gets shutdown.

If you have orphan nodes outside the tree that could also cause RID leaks because many nodes only delete their internal used RIDs when freed. E.g. if you have Area2D or PhysicsBody2D nodes outside the tree parked but not deleted when the game shutdown happens that might as well be the source of your errors here.