Firebase Firestore .add() returns 400 bad request after successful form submission (Flutter Web)

Question

I built a multi-tab Flutter Web registration form (Clients and Workers) that submits data to Firebase Firestore using the .add() method.

It was working fine for a few days, but now I'm getting this error in the console:

FirebaseError: FirebaseError: [code=invalid-argument]: Request is missing required field: write.operations

Here’s how I’m submitting data:

await FirebaseFirestore.instance.collection("registrations").add({
  "fullName": fullNameController.text.trim(),
  "email": emailController.text.trim(),
  // more fields...
});

What I Tried:

I used FirebaseFirestore.instance.collection("registrations").add({...}) to submit the form data.
Verified that all required fields have valid values before calling .add().
Ensured Firebase security rules are not blocking the request (allow read, write: if true;).
Simplified the data to just one key-value pair to check if it was due to large data — still failed.
Tested in Flutter Web (Chrome) — fails with the 400 invalid-argument error.
Tested the same code in Flutter Android emulator — works fine without error.
Also rechecked if any of the text controllers were null or empty.

What I Expected:

The .add() call should successfully create a new document in the registrations Firestore collection.
The Firestore backend should return the new document ID as usual.
No errors should appear in the browser console or terminal.

I suspect there may be something wrong with the values you're passing. Try it with hard-coded values, and if that works, print the values you're passing to Firestore to check them for empty/null/anything else unusual. — Frank van Puffelen
– Frank van Puffelen, Commented Jul 23 at 14:50
Please also edit your question and add the information Frank asked for. — Alex Mamo
– Alex Mamo, Commented Jul 24 at 7:57

Andreas Hadjimamas · Accepted Answer · 2025-07-29 12:01:30Z

0

If you are using cloud_firestore try the code below

await FirebaseFirestore.instance.collection("registrations").doc().set({
  "fullName": fullNameController.text.trim(),
  "email": emailController.text.trim(),
  // more fields...
});

answered Jul 29 at 12:01

Andreas Hadjimamas

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