Firebase Firestore Transaction Error: Cannot Modify A Writebatch That Has Been Committed

I am deploying on cloud functions, and getting this error Error: Cannot modify a WriteBatch that has been committed. at WriteBatch.verifyNotCommitted (/user_code/node_modules/fireb

Solution 1:

This was solved by using a for loop, as mentioned by @Renaud Tarnec in the comments.

I think your problem comes form the fact that you are returning several times the transaction into the forEach loop. Also you don't return the transaction when doing transaction.update(instanceDocRef, { user_size: newUserSize });. I would kindly suggest that you study into detail the documentation: https://firebase.google.com/docs/firestore/manage-data/transactions and https://firebase.google.com/docs/reference/js/firebase.firestore.Transaction. With the forEach loop I think that you are not following the constraint: "A transaction consists of any number of get() operations followed by any number of write operations such as set(), update(), or delete(). "