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HTML5 How to troubleshoot HTML5 issues


Hi, I am experiencing a very strange issue that I can't find a way to diagnose. Any help pointing me in any direction would be very helpful.

When I upload a new version of the HTML5 version of my game, the first time the user loads the game it is unresponsive.
Music plays, animations on screen work, but input is not detected. If you reload the page, the problem disappears and never happens again until a new update is uploaded.
This issue only happens with Chrome (tried Firefox and Edge and I cannot reproduce it).

You can try for yourself using this link: https://misterakuma.itch.io/pretend-cars

I've tried using the developer tools but I don't see anything unusual, same with the Debug mode in Gamemaker Studio. I am running the latest version of GMS2 and Chrome.

If someone has any idea of what I could try to identify the issue I would be forever grateful! This is driving me nuts : (

Thanks in advance.


Hey Ricardo! Thanks for the answer. Indeed I am doing that, but I am checking if the file exists, and creating a ds_map if it is not there. I'll post the code below.

I am not seeing that message in Gamemaker's debugger, or at least the game doesnt freeze when the file is not found, only if it is there but the game has been updated (the sav file is reused to track progression).

I checked Chrome's debugger and when the file doesnt exists it shows this (but wont freeze):
EAD https://v6p9d9t4.ssl.hwcdn.net/html/3072160/html5game/savedata-test.sav 403
Cannot read property 'substring' of null
cargado ds_map -> this is my debug message to check that the ds_map was created
Application Surface created: w=1366, h=768

Also, I've noticied that to make things stranger, when the game becomes unresponsive to key presses, changing focus from Chrome's tab and returning will unfreeze it...

file_name = "savedata.sav";

if (file_exists(file_name)) {
    if (!is_undefined(ds_map_find_value(saved_laptimes,"name"))) {
        global.name = ds_map_find_value(saved_laptimes,"name");
    } else {
        global.name="Player 1";
    if (!is_undefined(ds_map_find_value(saved_laptimes,"cup"))) {
        global.cupProgress = ds_map_find_value(saved_laptimes,"cup");
    } else {
        global.cupProgress=5; // para debug, sino 0
    show_debug_message("cargado ds_map");
} else {
    saved_laptimes = ds_map_create();
    global.name = "Player 1";
    global.cupProgress=5; // solo debug, deberia ser 0
    show_debug_message("no existia savedata");
Last edited:

True Valhalla

Full-Time Developer
GMC Elder
It's super important to test early and test often when you're working with HTML5; debugging this export is a nightmare. If you encounter a critical error that you simply can't trace, fall back on source control to pinpoint when the issue was originally introduced.


I try to but this is my first game and obviously I am learning a lot of things as I go, and I am not using source control : (
The bug is so strange and specific to Chrome that I cannot identify the cause no matter what I have tried. What threw me off completely was that only changing focus to another tab, or even the developer tool would make the game responsive again.