I saw old posts mentioning the problem but no solution so far. Is there something to modify in javascript so to make the game playable on Firefox?
What would be the alternative? with a download link?
I am a firefox user myself and never had any issues running GDevelop or GDevelop games 
that was very helpful
No. I have my game on itch.io as a browser game. I struggle to make it load faster and play faster. And also to make it work on Firefox. There it gets stuck in the loading screen forever. Maybe this screenshot can help.
While it shouldn’t necessarily cause it to not fully load, Firefox has had nonstandard (compared to other browsers) WebGL implementation for years, and it causes bugs in numerous different WebGL (and some canvas) apps. You can find both canvas and webGL rendering/crash/etc bugs dating back to a decade ago.
941146 - NS_ERROR_FAILURE when other browsers work fine when setting font on a canvas context in a display:none iframe Here’s a similar bug (canvas and webgl rendering crash) that’s been reported nearly a decade ago and still open.
Generally, Firefox should work fine, but GDevelop is mostly designed and tested for Chromium (both electron and chromium based browsers), so there could be bugs that people here won’t be able to detect/assist with.
Still no clue why it wouldn’t load at all, though.
From a read through of your error message, it seems to be erroring out on loading fonts/text objects.
You might try removing your text objects on your starting scene, or try changing them to another object type.
Thank you! So I should have a first scene with no text object? Like wait a second and switch to the second scene with the text?
No, I’d say test if it loads at all with no text objects.
If it works, that doesn’t necessarily mean a scene with text objects will. It could be anything anything from Firefox not supporting the positioning transform code for text, or if you’re using tints, or just something as simple as Firefox doesn’t support what is considered standard text rendering in WebGL/Canvas/etc.
You’ll need to see if you can get it to load at all first, then start narrowing down potential causes until it crashes. Then you can change how you’re doing X thing (Whereas X is whatever crashes) so Firefox loads your project for you.
So you’re right. The first scene with no text loads. Then it gets stuck on the one with the text.
What is “position transform code”? positioning the text and moving it in the code?
How did you see it was in the text by the way? thanks a lot! I spent hours looking online
would it be possible that the adult content is filtered? I’m using slang words. When I erase them it works. It’s kind of crazy
Unfortunately, I coudln’t tell you. As mentioned, since this is specific to firefox, it’s going to be something with how firefox deals with whatever is causing the issue.
The text is rendered at whatever position it originates at, then the positions are “transformed” to a new position, whether that’s moved, inverted, etc.
I looked thorugh the line and saw the first actual specific rendering thing mentioned (beyond just the basic renderer, which contains everything) was the PixiText object js file.
I can confirm Firefox filter the adult content. I don’t have any filter though. Same with my friends who tried. If I had chosen these filters then that would be okay. But this is terrible for Firefox in my opinion.
Anyway, what I did was to use autotyping and it worked, with the original text