Multiple transactions to same document failure in flutter firestore - firebase

Question

I am been trying to implement multiple transactions to the same document in flutter application which is using firestore as a its database, but it is crashing the application. The same thing when it was implemented in native apps of Xcode or android studio this issue didn't occur for even once.
Is there any guide how to make multiple transactions successful in flutter firestore.
For Instance, if more than 1 user from different devices is making the transaction to the same document at the same time, the transaction fails and the app crashes.
How could this be resolved?
Firestore.instance.runTransaction((Transaction tx) async {
DocumentSnapshot postSnapshot = await tx.get(docRef);
if (postSnapshot.exists) {
await tx.update(docRef, <String, dynamic>{'likes': postSnapshot.data['likes'] + 1});
// print("transaction completed");
}
})
ERROR LOGS
2020-05-27 18:43:14.529 1022-1344/dev.jideguru.social_app_ui
E/AndroidRuntime: FATAL EXCEPTION: AsyncTask #4 Process:
dev.jideguru.social_app_ui, PID: 1022 java.lang.RuntimeException: An
error occurred while executing doInBackground() at
android.os.AsyncTask$3.done(AsyncTask.java:353) at
java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:383)
at java.util.concurrent.FutureTask.setException(FutureTask.java:252)
at java.util.concurrent.FutureTask.run(FutureTask.java:271) at
android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:245) at
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1162)
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:636)
at java.lang.Thread.run(Thread.java:764) Caused by:
java.lang.AssertionError: INTERNAL ASSERTION FAILED: A transaction
object cannot be used after its update callback has been invoked. at
com.google.firebase.firestore.util.Assert.fail(com.google.firebase:firebase-firestore##21.3.0:46)
at
com.google.firebase.firestore.util.Assert.hardAssert(com.google.firebase:firebase-firestore##21.3.0:31)
at
com.google.firebase.firestore.core.Transaction.ensureCommitNotCalled(com.google.firebase:firebase-firestore##21.3.0:246)
at
com.google.firebase.firestore.core.Transaction.lookup(com.google.firebase:firebase-firestore##21.3.0:81)
at
com.google.firebase.firestore.Transaction.getAsync(com.google.firebase:firebase-firestore##21.3.0:191)
at
com.google.firebase.firestore.Transaction.get(com.google.firebase:firebase-firestore##21.3.0:228)
at
io.flutter.plugins.firebase.cloudfirestore.CloudFirestorePlugin$5.doInBackground(CloudFirestorePlugin.java:613)
at
io.flutter.plugins.firebase.cloudfirestore.CloudFirestorePlugin$5.doInBackground(CloudFirestorePlugin.java:608)
at android.os.AsyncTask$2.call(AsyncTask.java:333) at
java.util.concurrent.FutureTask.run(FutureTask.java:266) at
android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:245) at
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1162)
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:636)
at java.lang.Thread.run(Thread.java:764) 2020-05-27 18:43:14.529
1022-1346/dev.jideguru.social_app_ui E/AndroidRuntime: FATAL
EXCEPTION: AsyncTask #6 Process: dev.jideguru.social_app_ui, PID: 1022
java.lang.RuntimeException: An error occurred while executing
doInBackground() at android.os.AsyncTask$3.done(AsyncTask.java:353) at
java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:383)
at java.util.concurrent.FutureTask.setException(FutureTask.java:252)
at java.util.concurrent.FutureTask.run(FutureTask.java:271) at
android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:245) at
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1162)
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:636)
at java.lang.Thread.run(Thread.java:764) Caused by:
java.lang.AssertionError: INTERNAL ASSERTION FAILED: A transaction
object cannot be used after its update callback has been invoked. at
com.google.firebase.firestore.util.Assert.fail(com.google.firebase:firebase-firestore##21.3.0:46)
at
com.google.firebase.firestore.util.Assert.hardAssert(com.google.firebase:firebase-firestore##21.3.0:31)
at
com.google.firebase.firestore.core.Transaction.ensureCommitNotCalled(com.google.firebase:firebase-firestore##21.3.0:246)
at
com.google.firebase.firestore.core.Transaction.lookup(com.google.firebase:firebase-firestore##21.3.0:81)
at
com.google.firebase.firestore.Transaction.getAsync(com.google.firebase:firebase-firestore##21.3.0:191)
at
com.google.firebase.firestore.Transaction.get(com.google.firebase:firebase-firestore##21.3.0:228)
at
io.flutter.plugins.firebase.cloudfirestore.CloudFirestorePlugin$5.doInBackground(CloudFirestorePlugin.java:613)
at
io.flutter.plugins.firebase.cloudfirestore.CloudFirestorePlugin$5.doInBackground(CloudFirestorePlugin.java:608)
at android.os.AsyncTask$2.call(AsyncTask.java:333) at
java.util.concurrent.FutureTask.run(FutureTask.java:266) at
android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:245) at
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1162)
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:636)
at java.lang.Thread.run(Thread.java:764)
Link To the Issue

Answer 1

Caused by: java.lang.AssertionError: INTERNAL ASSERTION FAILED: A transaction object cannot be used after its update callback has been invoked.
It looks like the transaction is being used after it's been committed/canceled.
This is a known issue in the FlutterFire library, as recorded in this issue on the open-source repo.
There is a workaround mentioned in this comment. So you can either try to apply that to your case, propose a PR that fixes the bug, or wait until somebody else fixes it.