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[flutter_svg] Failed pending cache loads escape as unhandled errors and prevent retries #196285
Description
Steps to reproduce
- In the flutter_svg package on main, add and run the test below.
- Complete the first load with an error.
- Observe the unhandled asynchronous error. Then request the same key again with a successful loader; the failed pending future is reused and the loader is not called.
- To see the user-facing impact, load an SVG with SvgPicture.network while the connection drops. The errorBuilder runs, but the escaped error reaches PlatformDispatcher.onError.
Expected results
The future returned by putIfAbsent completes with the original error so callers can handle it. No separate unhandled asynchronous error reaches the zone or PlatformDispatcher.onError. The failed pending entry is removed, allowing a later request for the same key to retry.
Actual results
The success-only pendingResult.then callback creates a derived future with no error handler. When loading fails, that derived future surfaces an unhandled asynchronous error. The failed future also remains in _pending, so subsequent requests for the same key replay the failure instead of retrying.
With SvgPicture.network, errorBuilder runs, but the widget does not expose the escaped future for the application to catch. This can reach PlatformDispatcher.onError and be recorded by Crashlytics as a fatal error.
Related: dnfield/flutter_svg#881
Related PR: dnfield/flutter_svg#1104
Code sample
Code sample
import 'dart:async';
import 'package:flutter/foundation.dart';
import 'package:flutter_svg/src/cache.dart';
import 'package:flutter_test/flutter_test.dart';
void main() {
test('Failed load is evicted from pending and retried', () async {
final cache = Cache();
final error = StateError('boom');
final completer = Completer<ByteData>();
final Future<ByteData> future = cache.putIfAbsent(
'key',
() => completer.future,
);
completer.completeError(error);
await expectLater(future, throwsA(same(error)));
await null;
var calls = 0;
await cache.putIfAbsent('key', () async {
calls++;
return ByteData(1);
});
expect(calls, 1);
});
}Screenshots or Video
Screenshots / Video demonstration
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Logs
Logs
Reproduced on main: running the test above fails with an unhandled Bad state: boom error.
With the fix, flutter test test/cache_test.dart passes (5 tests).Flutter Doctor output
Doctor output
[✓] Flutter (Channel stable, 3.47.9, on Ubuntu 24.04.5 LTS 6.8.0-1064-azure,
locale C.UTF-8) [39ms]
• Flutter version 3.47.9 on channel stable at /home/codespace/flutter
• Upstream repository https://github.com/flutter/flutter.git
• Framework revision c197ca5199 (12 days ago), 2026-10-29 10:10:20 -0400
• Engine revision 89c39edfdf
• Dart version 3.13.7
• DevTools version 2.60.0
• Feature flags: enable-web, enable-linux-desktop, enable-macos-desktop,
enable-windows-desktop, enable-android, enable-ios, cli-animations,
enable-native-assets, enable-record-use, enable-swift-package-manager,
omit-legacy-version-file, enable-lldb-debugging, enable-uiscene-migration
[✗] Android toolchain - develop for Android devices [30ms]
✗ Unable to locate Android SDK.
Install Android Studio from:
https://developer.android.com/studio/index.html
On first launch it will assist you in installing the Android SDK
components.
(or visit https://flutter.dev/to/linux-android-setup for detailed
instructions).
If the Android SDK has been installed to a custom location, please use
`flutter config --android-sdk` to update to that location.
[✗] Chrome - develop for the web (Cannot find Chrome executable at
google-chrome) [13ms]
! Cannot find Chrome. Try setting CHROME_EXECUTABLE to a Chrome executable.
[✗] Linux toolchain - develop for Linux desktop [186ms]
• Ubuntu clang version 18.1.3 (1ubuntu1)
• cmake version 3.28.3
✗ ninja is required for Linux development.
It is likely available from your distribution (e.g.: apt install
ninja-build), or can be downloaded from
https://github.com/ninja-build/ninja/releases
• pkg-config version 1.8.1
✗ GTK 3.0 development libraries are required for Linux development.
They are likely available from your distribution (e.g.: apt install
libgtk-3-dev)
! Unable to access driver information using 'eglinfo'.
It is likely available from your distribution (e.g.: apt install
mesa-utils)
[✓] Connected device (1 available) [46ms]
• Linux (desktop) • linux • linux-x64 • Ubuntu 24.04.5 LTS 6.8.0-1064-azure
[✓] Network resources [289ms]
! Doctor found issues in 3 categories.
Activity
mbcorona commentedon Nov 10, 2026
Thanks for the report and the test @deandreamatias.
Routing to the engine team to review the PR.