FCM getting MismatchSenderId

Question

I have an application that uses Google FCM for sending push notifications.

When i send a push notification to a group of users, i get a response of MismatchSen

Answer 1

I wasted days on this.

In my case, I followed this blog to use Postman and get the mismatchsenderid error. Previously, I was getting messaging/mismatched-credential, and people reported that their client app used multiple projects.

However, for me, I have one-to-one, a web app and a project. BUT, I host all apps via ng serve on default port 4200. So regardless of what project / app pair I was developing on, I would always get the same token from my client web app using AngularFireMessaging.requestToken - this token was always the token created on my first ever run of a firebase app in development.

As a work around, I start different apps / projects on different ports and get proper tokens for respective projects.

Answer 2

I have noticed that when a device id is created in GCM you cannot send push messages through FCM using the new server key, you have to use the old API-key.

Answer 3

Firebase has upgraded their server keys to new version. Use new keys instead of old one.

go to settings->project settings->cloud messaging tab

Answer 4

I found that the senderId is different from the project number in the FCM console
so I re-downloaded google-services.json and everything works fine

Answer 5

I had the same error while trying to send push notificaion. Get the updated google-services.json file and replaced with it. Worked for me.

Answer 6

I found this solution:

• First I check server key is correct or not it was correct which is like AIzaXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
• Then I check Sender Id like 79XXXXXXXX it was also correct.
• Main issue was in device_ID(UDID) to whom I have to send the notification. Actually DeviceId we got on android side in FCM is different than GCM. You can't use GCM created DeviceId in FCM.