Fix: GameMaker Network Async Event Buffer Pointer Invalid

If you are searching for how to fix gamemaker network async event buffer pointer invalid, you are not alone. This is a recurring issue in GameMaker that comes up across many team projects. The behavior looks like a deep bug, but it usually traces back to a known interaction between two systems. Here is the full breakdown of the symptom, the cause, and a fix you can apply today.

The Symptom

You store the buffer pointer from async_load[?"buffer"] in an instance variable for processing later. When you read from it in a subsequent step, the game crashes with an invalid pointer error.

Root Cause

GameMaker's Async Networking event passes a temporary buffer that's deallocated when the event handler returns. Storing the pointer captures only the address; the underlying memory is freed by the runtime.

The Fix

Step 1: Copy the buffer contents into a new buffer you own: var my_buf = buffer_create(...); buffer_copy(async_load[?'buffer'], 0, size, my_buf, 0).

// Async Networking event - copy buffer immediately
var src = async_load[? "buffer"];
var size = async_load[? "size"];
if (src != undefined && size > 0) {
    incoming_buffer = buffer_create(size, buffer_fixed, 1);
    buffer_copy(src, 0, size, incoming_buffer, 0);
    // Now safe to use incoming_buffer in later events
}

Step 2: Process all data within the Async Networking event itself - don't defer reading to a later step.

// Process and free later
if (incoming_buffer != undefined) {
    buffer_seek(incoming_buffer, buffer_seek_start, 0);
    var msg_type = buffer_read(incoming_buffer, buffer_u8);
    handle_message(msg_type, incoming_buffer);
    buffer_delete(incoming_buffer);
    incoming_buffer = undefined;
}

Step 3: If you need to forward the data to another instance, use ds_queue with buffer-of-bytes copies rather than pointer passing.

Check the boundary; the bug lives between systems.