returns Error 400

Please provide the following:

  1. SDK Version:46
  2. Platforms(Android/iOS/web/all):all
  3. Add the appropriate “Tag” based on what Expo library you have a question on.

Hi, i currently have an Expo App, when app opens i get the users permission to send notifications and store both their expo push token and device push token in my firestore database.

I also, have a react app where i want to send these users a notification. In my web app, i have 2 input boxes 1 for title and the other for body. When i try sending them i keep getting error code 400, i tried adding a proxy in the web app and still the same error occurs.

Here is my code

 const message = {
                to: tokens,
                sound: "default",
                data: {
                    experienceId: '@owner/slug',
                    scopeKey: '@owner/slug',
                    title: title,
                    message: body,

const response = await fetch('', {
                method: 'POST',
                headers: {
                  'Content-Type': 'application/json',
                  Authorization: `key=${process.env.REACT_APP_FCM_SERVER_KEY}`,
                body: JSON.stringify(message),

                    try {
                    const docRef = await addDoc(collection(db, "broadcast"), {
                        title: title,
                    console.log("Document written with ID: ",;
                    toast.success(`broadcast ${title} sent.`, {position: "top-right",})
                  } catch (e) {
                    console.error("Error adding document: ", e);
                    toast.error(e, {position: "top-right",})