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[tool_crash] _TypeError (Null check operator used on a null value) in ResidentHandlers.debugDumpFocusTree #192934
Description
Description
In Flutter 3.47.3 crash telemetry, ResidentHandlers.debugDumpFocusTree threw an unhandled _TypeError: Null check operator used on a null value (28 crashes in the first 7 days post-release).
Stack Trace
ResidentHandlers.debugDumpFocusTree at package:flutter_tools/src/resident_runner.dart:628
TerminalHandler._commonTerminalInputHandler at package:flutter_tools/src/resident_runner.dart:1832
TerminalHandler.processTerminalInput at package:flutter_tools/src/resident_runner.dart:1937
Cause
In package:flutter_tools/src/resident_runner.dart:
Future<bool> debugDumpFocusTree() async {
if (!supportsServiceProtocol || !isRunningDebug) {
return false;
}
for (final FlutterDevice? device in flutterDevices) {
final List<FlutterView> views = await device!.vmService!.getFlutterViews();
for (final view in views) {
final String data = await device.vmService!.flutterDebugDumpFocusTree(
isolateId: view.uiIsolate!.id!,
);
logger.printStatus(data);
}
}
return true;
}Force unwrapping view.uiIsolate!.id! (or device!.vmService!) throws a null check operator exception if view.uiIsolate is null (e.g. before the isolate finishes initializing or during teardown). Note that debugDumpLayerTree has the identical pattern.
Proposed Fix
Guard view.uiIsolate?.id and device?.vmService with null checks before invoking service extension methods.
Activity
[flutter_tools] Guard against null vmService and uiIsolate in debugDu…
[beta] [flutter_tools] Guard against null vmService and uiIsolate in …
[stable] [flutter_tools] Guard against null vmService and uiIsolate i…
Sync CHANGELOG.md from stable (flutter#195337)
[flutter_tools] Guard against null vmService and uiIsolate in debugDu…
Sync CHANGELOG.md from stable (flutter#195337)
github-actions commentedon Oct 30, 2026
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