How to get the matchmaker data for a new backfill player in-game? Gamelift Help

onUpdateGameSession callback request would be used to pass an updated game session object to the server process.

onUpdateGameSession – Name of callback function that the Amazon GameLift service invokes to pass an updated game session object to the server process. Amazon GameLift calls this function when a match backfill request has been processed in order to provide updated matchmaker data. It passes a GameSession object, a status update (updateReason), and the match backfill ticket ID.

Kindly refer the diagram in this documentation which shows GameLift and game client server interactions.

Additionally, you can check below documentations for further details on GameLift server SDK references:

[+] https://docs.aws.amazon.com/gamelift/latest/developerguide/gamelift-sdk-server-api.html

[+] https://docs.aws.amazon.com/gamelift/latest/developerguide/integration-server-sdk-cpp-ref-actions.html

If you have configured it and still observing discrepancies then we would require details that are non-public information i.e details that are specific to the custom setup/implementations in AWS account. Hence, you can open a support case with AWS using the following link