On January 31, 2019, FCM engineers rolled out a bugfix to improve the accuracy of the FCM reporting dashboard. Internally, FCM rejects sends to devices that haven’t connected to Google’s servers within 28 days. Before this fix, these rejects were incorrectly included in the sent counts on the FCM reporting dashboard. This change fixes that behavior.
Data reported before January 30, 2019 will not be backfilled with the bugfix. Therefore, some apps, specifically those that are sending to a large number of end users with devices that haven’t been online in a month or more, may see an apparent decrease in sent counts of 10% or more starting on that date. The actual number of successfully sent notifications will not change.
The bug only affected the FCM reporting dashboard. FCM data exported to BigQuery is not impacted by this change.
How does this affect me?
You may see a sudden drop in your FCM sent counts. This doesn’t affect the actual number of messages that were sent.
If you’d like to learn how to do your own FCM reporting, check out some sample BigQuery queries.