Godot: ERROR: _process_rset: Condition ' !_can_call_mode(p_node, rset_mode, p_from) ' is true

[marsmoon]

Godot 3.1 dd5398ce9dc49d1562faab5504f3923883d461a0

I get this error when I use rset in multiplayer:
ERROR: _process_rset: Condition ' !_can_call_mode(p_node, rset_mode, p_from) ' is true. At: core/io/multiplayer_api.cpp:314.

Code:

slave var slave_pos = Vector2()
slave var slave_rot = 0

func _process(delta):
    if is_network_master():     
        rset("slave_pos", position)
        rset("slave_rot", rotation)
    else:
        position = slave_pos
        rotation = slave_rot

What is causing this?

[akien-mga]

CC @Faless @mhilbrunner

[Faless]

@marsmoon are you properly setting network_master on both peers? I.e. if you set_network_master(client_id) for that node in the client, you also need to set_network_master(that_same_client_id) in the server.
That error is thrown when an RPC/RSET is received from a peer that is not allowed to call it.

[marsmoon]

I wasn't. I thought I only needed to set it once as in this example from the docs https://godot.readthedocs.io/en/latest/tutorials/networking/high_level_multiplayer.html. Thanks!

[Faless]

I guess documentation should be updated by adding:

player.set_network_master(p)

in the network master code listing (after player.set_name(str(p)))

[mhilbrunner]

@Faless I plan to rework the multiplayer docs for 3.1 once we finalized all the networking changes. All the awesome new stuff (like custom_multiplayer, new keywords) needs to be explained.

[mhilbrunner]

Maybe we should make a point to add clear error messages and logs to the networking though.

[Faless]

Maybe we should make a point to add clear error messages and logs to the networking though.

Yeah, we could replace the various ERR_FAIL_COND with:

if (cond) {
  ERR_EXPLAIN("Clear error message");
  ERR_FAIL(); // or ERR_FAIL_V (when needed)
}

[neikeq]

Yeah, we could replace the various ERR_FAIL_COND with:

if (cond) {
  ERR_EXPLAIN("Clear error message");
  ERR_FAIL(); // or ERR_FAIL_V (when needed)
}

I've found out recently that ERR_FAIL and ERR_FAIL_V do not use the message from ERR_EXPLAIN. Not sure if a bug or intended.

[akien-mga]

Usually it's done as:

if (cond) {
  ERR_EXPLAIN("Clear error message");
  ERR_FAIL_COND(cond); // or ERR_FAIL_COND_V (when needed)
}

I guess the rationale is that if you're failing all the times (no _COND), there's no need for more explanations... Don't know, maybe that could use some improvement :)

[Faless]

@akien-mga @neikeq

No need to re-evaluate the condition since you already tested in the if. ERR_FAIL(); or ERR_FAIL_V(ret_val); should be enough, if it no longer shows the message it's a bug, it used to, and it's widely used in the core. See for example https://github.com/godotengine/godot/blob/612ab4bbc6f2396f4dcd68c3f142f7dfa2f5f0a5/core/color.cpp#L279 https://github.com/godotengine/godot/blob/612ab4bbc6f2396f4dcd68c3f142f7dfa2f5f0a5/core/io/ip_address.cpp#L82

[neikeq]

EDIT: Never mind... I can't reproduce this anymore. No idea what I was doing wrong yesterday, but I remember checking this well and replacing the following code...

ERR_EXPLAIN("...");
ERR_FAIL_V(NULL);
// with
ERR_EXPLAIN("...");
ERR_FAIL_COND_V(true, NULL);

...made it display the message. Weird. Sorry for the false warning...

[Faless]

Errors are now (well actually, for a while now) more explicit (comes with EXPLAIN).
Once the docs PR is merged this can be closed I guess.

[tree786]

I got the same error message (3.1 and 3.1.1 stable), and it took some time until I understood that the instanced nodes (spawned in a multiplayer game) must have their name set to their network ID node.name=str(get_tree().get_network_unique_id()), and setting it to any other name does not work (at least from the simple tests I carried out). This is subtly mentioned in the documention (High level multiplayer), but it needs more emphasis imo.