Problem run Flutter Web app in our company network

Question

I'm trying to run my Flutter Web app on Local Area Network (intranet) in my work. But there is no internet access. And I have this issue “ Failed to load resource: net :: ERR_INTERNET_DISCONNECTED “. I think, problem is with canvaskit.js because my app try to download from internet. Do you have some idea how to fix it?

Answer 1

This is a common mistake when you use Flutter web within an Intranet that has no Internet access. I will try to explain it in detail.

In Flutter Web you can choose between two web renderers (more info here). The default one is CanvasKit, but there is also the HTML renderer.

The problem with CanvasKit web renderer is that when you start the application for the first time, it goes to unpkg.com and downloads two files: canvaskit.js and canvskit.wasm. Once downloaded, the browser caches them and Flutter doesn't need to download them again in the future.

But, if the app can't download these files, the application fails to start. Which is the problem that @TomášTorok mentions.

What are the solutions? There are two possibilities:

1 - Force your app to use the HTML web renderer, as it doesn't need to download anything over the Internet. This web renderer has some limitations that CanvasKit doesn't have, and vice versa (in this article they explain everything in detail)

To use the HTML in debug:

flutter run -d chrome --web-renderer html

OR if you want to build your app:

flutter build web --web-renderer html

2 - Download manually the canvaskit.js and canvaskit.wasm files from unpkg.com (example link), add them inside your project (inside /web folder), and force Flutter web to grab the local files and not download anything from the Internet.

It's a bit more work, but it's not complex either. You have the instructions in this link.

Answer 2

If I understood correctly;

There is nothing to do with flutter version or flutter channel. The error message is clearly explaining that internet is disconnected. The universal truth is you need a minimum speed internet to debug or release your flutter code development. Try to check the internet connection.

Reply back if this answer is helpful to you, also share how did you solved the issue.

Answer 3

The issue is to gracefully show a message that there is no internet - not have a frozen splash screen on the web.

I understand that the app itself needs the web to start - yet one can lose the internet just at app start, before these resources load...