Fatal Exception: Tried to finish non-existent task with id 1

[RodolfoGS]

I have a lot of crashes on Crashlytics related to headless. Says that can't stop a non-existent task.
I don't know how to reproduce the crash. I'm seeing them on Crashlytics.

My headless task is this:

BackgroundFetch.configure({
  minimumFetchInterval: 15,     // <-- minutes (15 is minimum allowed)
  forceAlarmManager: false,     // <-- Set true to bypass JobScheduler.
  stopOnTerminate: false,
  startOnBoot: true,
  requiredNetworkType: BackgroundFetch.NETWORK_TYPE_NONE, // Default
  requiresCharging: false,      // Default
  requiresDeviceIdle: false,    // Default
  requiresBatteryNotLow: false, // Default
  requiresStorageNotLow: false, // Default
  enableHeadless: true,
}, async (taskId) => {
  // event callback

  // ... my task is here

  BackgroundFetch.finish(taskId);
}, async (taskId) => {
  // task timeout callback
  console.log(`react-native-background-fetch timeout task: ${taskId}`);
  BackgroundFetch.finish(taskId);
});

BackgroundFetch.registerHeadlessTask(async (event) => {
  if (event.timeout) {
    BackgroundFetch.finish(event.taskId);
    return;
  }

  // ... my task is here

  BackgroundFetch.finish(event.taskId);
});

Your Environment

• Plugin version: 4.0.3
• Platform: Android
• OS version: 8, 9, 10, 11
• Device manufacturer / model: Samsung, Umx, Tinno, LGE, Motorola, Google, etc
• React Native version (react-native -v): 0.63.4

Expected Behavior

No crash

Actual Behavior

Crash

Steps to Reproduce

I don't know how to reproduce the crash, I have them on Crashlytics

Context

Run a headless task

Debug logs

Fatal Exception: java.lang.AssertionError: Tried to finish non-existent task with id 1.
       at com.facebook.infer.annotation.Assertions.assertCondition(Assertions.java:72)
       at com.facebook.react.jstasks.HeadlessJsTaskContext.finishTask(HeadlessJsTaskContext.java:173)
       at com.facebook.react.jstasks.HeadlessJsTaskContext$3.run(HeadlessJsTaskContext.java:211)
       at android.os.Handler.handleCallback(Handler.java:873)
       at android.os.Handler.dispatchMessage(Handler.java:99)
       at android.os.Looper.loop(Looper.java:193)
       at android.app.ActivityThread.main(ActivityThread.java:6746)
       at java.lang.reflect.Method.invoke(Method.java)
       at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)

[christocracy]

Show me your entire index.js without redaction.

[RodolfoGS]

@christocracy this is my index.js and a helper that I'm using to register the task

index.js

import 'react-native-gesture-handler'; 
import { Platform } from 'react-native';
import { registerRootComponent } from 'expo';
import App from './App';
import BackgroundFetch from './helpers/background-fetch';

if (Platform.OS === 'android') {
  BackgroundFetch.registerHeadless();
}

// registerRootComponent calls AppRegistry.registerComponent('main', () => App);
// It also ensures that whether you load the app in Expo Go or in a native build,
// the environment is set up appropriately
registerRootComponent(App);

---

helpers/background-fetch.js

import BackgroundFetch from 'react-native-background-fetch';

async function run() {
  // my task
}

function register() {
  BackgroundFetch.configure({
    minimumFetchInterval: 15,     // <-- minutes (15 is minimum allowed)
    forceAlarmManager: false,     // <-- Set true to bypass JobScheduler.
    stopOnTerminate: false,
    startOnBoot: true,
    requiredNetworkType: BackgroundFetch.NETWORK_TYPE_NONE, // Default
    requiresCharging: false,      // Default
    requiresDeviceIdle: false,    // Default
    requiresBatteryNotLow: false, // Default
    requiresStorageNotLow: false, // Default
    enableHeadless: true,
  }, async (taskId) => {
    // event callback
    await run();
    BackgroundFetch.finish(taskId);
  }, async (taskId) => {
    // task timeout callback
    console.log(`react-native-background-fetch timeout task: ${taskId}`);
    BackgroundFetch.finish(taskId);
  });

  // Query the authorization status
  BackgroundFetch.status((status) => {
    switch(status) {
      case BackgroundFetch.STATUS_RESTRICTED:
        console.log("react-native-background-fetch: BackgroundFetch restricted");
        break;
      case BackgroundFetch.STATUS_DENIED:
        console.log("react-native-background-fetch: BackgroundFetch denied");
        break;
      case BackgroundFetch.STATUS_AVAILABLE:
        console.log("react-native-background-fetch: BackgroundFetch is enabled");
        break;
    }
  });
}

function registerHeadless() {
  BackgroundFetch.registerHeadlessTask(async (event) => {
    if (event.timeout) {
      BackgroundFetch.finish(event.taskId);
      return;
    }

    await run();
    BackgroundFetch.finish(event.taskId);
  });
}

export default {
  register,
  registerHeadless,
}

[christocracy]

This error has been reported by others not using my plugins.

The stacktrace does not reference com.transistorsoft so I don't think my plugin is involved with the error. I don't see how my code could possibly catch that exception. The plugin is not involved with calling this RN finishTask method. This is purely RN plumbing at fault here.

[RodolfoGS]

The exception is fired by react-native in this line, when try to finish the task.

Maybe could be fixed adding an if using the method isTaskRunning to verify if the task is running before call finishTask?

Could be a race condition with event.timeout?

[christocracy]

to verify if the task is running before call finishTask?

My code does not call finishTask. RN calls that upon itself.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions. You may also mark this issue as a "discussion" and I will leave this open.

[stale]

Closing this issue after a prolonged period of inactivity. Fell free to reopen this issue, if this still affecting you.

[Saad-Bashar]

@RodolfoGS Just trying out my luck here. Apologies for posting a comment here. Did any of you figure out a solution on this? We are using react-native-background-fetch as well and recently getting a lot of crash with this message. The crash mainly happens on Samsung android. I know this library is not responsible for that but hoping to get some hints. Thanks!