Invalid access to property or key on a base object of type 'Nil' in Godot 4

GDScript compiles player.position to a named property read. At run time the virtual machine asks the value held in player for its position property. When that value has no such property, the function stops and Godot prints this error with the property's name and the type it found.

'Nil' is the name of the empty Variant type: the variable holds nothing at all. A typed variable of an Object type, such as var player: Node2D, starts out holding Nil and keeps it until a line assigns it. The type annotation says what player may hold; it does not create a node.

The same check names the base differently for the other two ways a reference can be empty: 'null instance' when the variable holds an Object reference that points at nothing, which is what $Player and get_node_or_null give you when the node is missing, and 'previously freed' when the object was freed. Each has its own page, linked below.

The function stops at the failing line. In the run below, the print after it never ran.

A node script that declares a typed variable and reads a property from it before anything has assigned it. The scene is one Node with this script.

Export the variable and assign it in the Inspector: here the scene has a Node2D child named Player, and the exported field points at it. The check before use turns a forgotten assignment into a message that names the node, instead of a crash at the first property read.

Godot calls _ready on children before their parent. If a parent's _ready assigns a child's variable, the child's own _ready runs first and reads it while it is still Nil. Read it later, in a function the parent calls after assigning it, or have the child find what it needs itself with get_node or an @export.

An exported field is set per node in the scene. Assigning it on one instance does not assign it on another instance of the same scene, or on a node you create with instantiate() in code. The check in the fix above names the node, so the log tells you which one.

Godot 4.0 to 4.2, and Godot 3, printed it as: Invalid get index 'position' (on base: 'Nil'). The cause and the fix are the same.

Both scripts on this page were run headless on Godot 4.7.2 (4.7.2.stable.mono.official.ed1daf0bf) on 6 October 2026, and the output above is what Godot printed, unedited.

Where the check lives in Godot's source: [gdscript_vm.cpp line 1281, the message](https://github.com/godotengine/godot/blob/4.7.2-stable/modules/gdscript/gdscript_vm.cpp#L1281), [gdscript_vm.cpp lines 62 to 72, how the base type is named](https://github.com/godotengine/godot/blob/4.7.2-stable/modules/gdscript/gdscript_vm.cpp#L62-L72).