Example Code for Isolates in Flutter Cookbook Fails Due to NetworkImageLoadException.

[Turskyi]

Page URL

https://docs.flutter.dev/cookbook/networking/background-parsing/

Page source

https://github.com/flutter/website/tree/main/src/content/cookbook/networking/background-parsing.md

Describe the problem

I followed the example provided in the Flutter Cookbook for using isolates to perform background parsing (https://docs.flutter.dev/cookbook/networking/background-parsing). However, when running the code on an iOS simulator, I encountered multiple NetworkImageLoadException errors. The console logs indicate HTTP 504 errors for the placeholder image URLs, resulting in the UI displaying “http request failed” squares instead of the expected images.

Expected fix

The example should use reliable image URLs or include a fallback mechanism to handle image loading failures gracefully. This would ensure that the example works as intended and matches the preview GIF shown in the documentation.

Additional context

Here are the specific errors from the console:
======== Exception caught by image resource service ================================================ The following NetworkImageLoadException was thrown resolving an image codec: HTTP request failed, statusCode: 504, https://via.placeholder.com/150/56a8c2 ...
This issue affects the usability of the example and may confuse users who are trying to learn from the documentation. Providing a working example is crucial for a professional and educational experience.

I would like to fix this problem.

• I will try and fix this problem on docs.flutter.dev.