Mismatch Sender ID

For those users who may have added a custom GCM/FCM ID and Key, sometimes you may get a warning when sending a campaign stating some notifications were not deliverable due to a "Mismatch Sender ID".

This essentially means that those push subscribers are active but we were unable to reach them due to a technical set up issue. While we do our best to provide you with a background and solutions below, this may become technical so feel free to reach out to your account manager for support.


To provide a quick background to help in understanding, there are generally 4 areas that are needed to send a notification to a subscriber:

(1) Subscriber ID + (2) Subscriber Push Token + (3) GCM ID* + (4) GCM Key = Success Push

To help make it easy for you (the user of the software), most push provider handle all of this in the background and set you up with a pair of default GCM IDs or GCM Keys or show you how to add them (adding a correct GCM/FCM ID).

*also commonly referred to as FCM ID or Sender ID

Reasons & Solutions:

Reason #1: You did not add the correct GCM key in your Aimtell dashboard

This scenario usually occurs if you are moving from another push provider to Aimtell.

In this case, a website visitor may have already given you permission to send them notifications so when they visit your site Aimtell will automatically add them as a subscriber. The issue, however, is that their subscription is tied to another GCM ID (see #3 in Background above).

In order to send a push to that subscriber, we need the corresponding GCM ID + GCM Key. If you have these, simply double check that you've added the correct GCM/FCM ID and Key in your Aimtell dashboard. If you do not have these, ask your old push provider to provide them.

Reason #2: You have a conflicting manifest file

When a website visitor subscribes to push notifications on your website they are automatically attached to your website's Sender ID (aka GCM or FCM ID). While this Sender ID is specified within your Aimtell dashboard, it can also be manually set with a "manifest" file on your website.

If you have a manifest file on your website with a different Sender ID than what is stated in your Aimtell dashboard, it will likely cause a Mismatch Sender error. To fix this, simply make sure these two IDs are the same.

Reason #3: You removed a valid, existing Sender ID/Key from Aimtell

Let's say you set your Sender ID to 461783654421 within the Aimtell dashboard and collected a few subscribers. Then, sometime later, you deleted that ID and added a new one - 238646170294.

When sending a push you may likely have this issue since those initial subscribers are all attached to 461783654421 but that ID and Key no longer exists in Aimtell. To fix this, simply add the original Sender ID and Key back into your account.

Note: You can have multiple Sender IDs and Keys under your account, and toggle which one is the primary (aka which all new subscribers should be attached to)

While the system will automatically attempt to update subscribers affected by the Mismatch Sender ID issue to the correct GCM ID and Key, sometimes this can take some time.

If you'd like to speed up the process, contact support@aimtell.com and we will manually update your subscribers for you.