[FirestoreCollection.update] Error 2 (UPDATE DOCUMENT) when calling update() in send_move()

[Shay-M]

Environment

• Godot Engine: 4.4.1.stable.official

• godot-firebase plugin version: 2.1 (godot asset-lib addon)

• Platform: Windows

• Firebase rules:

  rules_version = '2';
  service cloud.firestore {
    match /databases/{database}/documents {
      allow read, write: if request.time < timestamp.date(2025, 7, 24);
    }
  }

What I’m Trying to Do

In my turn‑based multiplayer, when the local player finishes a move I call:

# Singleton (autoload)

var coll: FirestoreCollection = Firebase.Firestore.collection("games")
var doc_ref: FirestoreDocument = await coll.add("", payload)
_listening_doc_ref = doc_ref

func send_move(move_path: Array, next_turn_uid: String) -> void:
    var coll: FirestoreCollection = Firebase.Firestore.collection("games")
    _listening_doc_ref.add_or_update_field("last_move", move_path)
    _listening_doc_ref.add_or_update_field("current_turn_uid", next_turn_uid)
    await coll.update(_listening_doc_ref)
    print("Sent move on", _listening_doc_ref.doc_name)

I get:

ERROR: [Firebase Error] >> Action in error was: 2 (UPDATE DOCUMENT)

and the update() returns null.

What I’ve Tried

• Switched to using collection.set_doc(doc_id, updates) instead of update() → same Action in error was: 2
• Added an .error listener on the FirestoreCollection signal to print err.code/err.message → nothing extra appears
• Verified that _listening_doc_ref.doc_name exists in the games collection immediately prior to the call
• Added small delays (await get_tree().create_timer(0.5).timeout) to ensure the document is in cache/listener

Relevant Log Snippet

NetworkPlayerAgent: request_move() — waiting for opponent to move...
App returned to foreground
NetworkPlayerAgent: send_local_player_move() called with path=[(4.0,1.0)]
a: sending move [(4.0, 1.0)] with next turn vGTik1s...
a: live update → { … current_turn_uid: "tEJ…", last_move: [(4.0,1.0)], … }
ERROR: [Firebase Error] >> Action in error was: 2 (UPDATE DOCUMENT)

Code for My FirestoreCollection.update

	if not coll.is_connected("error", _on_firestore_error):
		coll.connect("error", _on_firestore_error)

func _on_firestore_error(err: Dictionary) -> void:
	print("Firestore error")
	printerr("%s: FirestoreCollection.error → code=%s, message=%s, details=%s"
		% [current_user_name,
			err.get("code"),
			err.get("message"),
			err])

Questions / What I Need Help With

1. What does Error 2 (UPDATE DOCUMENT) mean under the hood?
2. Why is update() returning null instead of a valid FirestoreDocument?
3. Am I missing some required field paths in that updateMask.fieldPaths URL?
4. Is there some internal plugin limitation on patching arrays or nested fields?

Any pointers or suggestions how to diagnose this (e.g. additional debug flags, HTTP inspection, plugin internals) would be greatly appreciated! Thank you.

[Shay-M]

I discovered the culprit was indeed the array shape . Firestore wasn’t handling an array of Vector2s (or nested arrays). Converting your path to a flat Array of ints (e.g. [x1, y1, x2, y2, …]) before sending, and then reconstructing Vector2s on receipt, fixes the “UPDATE DOCUMENT” errors.

[WolfgangSenff]

Oh interesting. I'm sorry, thought I replied to this. That's annoying. Any chance you can open a PR to fix it?