Matchmaking event of type MatchmakingSucceeded did not contain player session ids of new incoming players

Recently I believe I may have stumbled across a glitch where an event of type MatchmakingSucceeded did not have the player session ids of the new incoming players. I do want to note that this matchmaking request was a manual backfill request so I am not sure if that had anything to do with it. I just want to make sure that this is a glitch or if something I did caused this to happen. And if need be, for further investigation, I can pm someone information about the match and players involved because I have the event message recorded.

Can you provide matchmaking ticket ids and I can get the GameLift service team to investigate?

Yes, here are the tickets associated with the event:


Thanks I’ve opened an issue with the GameLift team.

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We recently deployed an improvement to the GameLift service that targets missing player session IDs in matchmaker responses. We expect missing player session IDs to no longer occur. Please let us know if you still see this issue over the next 2-3 weeks!

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I recently noticed this issue too. Players that leave the session or time out are still reported in backfill messages but don’t have a player session.

Is this still going to be expected behavior or will this be changing somehow?

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@ig_tyler - If you have examples of matchmaking ticket ids / game session ids that you think aren’t working correctly, I can get the GameLift service team to take a look (if its an urgent issue, please open an issue through AWS support).

Seems strange to have player data without a player session id on a game session update. As you mention that this is impacting players who’ve left / timed out on connect, this may due to the fact that your game server is currently responsible for updating the player data in this circumstance and I wonder if there is stale data being sent with the request.

I can confirm that what @ig_tyler is saying. If there is a backfill request involving a player whose player session is timedout or completed, then when that backfill request gets fulfilled, the matchmaking succeeded event sent to the matchmaker’s notification sns topic target still has that player but without its player session id.

@chrisgong: Do you have any example matchmaking ticket ids or player session ids? Would like to pass this information on to the GameLift team.

Hey @Pip, here is a ticket id for a backfill request that describe this situation.


I believe what happened exactly was that there was a situation in which a player left the game, and a backfill request was made with the remaining players. Then, one of the remaining players also left but the backfill request in progress was not cancelled. Therefore, players could get matched with this backfill ticket that was not truly representative of the players still in the game.

I don’t know if this is necessarily good or bad behavior, since I found a way around this by cancelling backfill requests whenever players leave the game. In my case, I terminate the player session when a player leaves, so eventually a new backfill request gets made with the remaining players in the game.

I looked into what happened to that ticket. It was exactly like what you described. The player session was already completed by the time the match was formed.

FlexMatch assumes the players in match making tickets are accurate, so it currently records this abnormal case and returns a ticket with missing player session IDs.

Your method of canceling the backfill request when players leave the game is the right approach.