GameLiftServerAPI.AcceptPlayerSession() always returns true

Question

I'm using the latest 5.1.2 version of the GameLift server SDK for C# and observing a buggy behavior in the SDK: Upon having a client connect, my server receives the player session ID from the client, which it uses as argument to `GameLiftServerSDK.AcceptPlayerSession("psess-....")`. I would expect that the method would only succeed for valid player sessions with state `RESERVED` and only for player sessions that are registered for the specific server's game session. However, it turns out that the method _always_ returns successful, also for expired player session IDs, or for completely invalid ones (random strings). In the server logs, it is visible that the method returns successfully _before_ GameLift APIs respond with the actual response, i.e. the game server accepts the client before receiving the actual response from GameLift (which seems to be discarded?).

Here's a snippet of the log from my GameLift-hosted server instance:

```
456214 [Thread Pool Worker] DEBUG Aws.GameLift.Server.ServerState (null) - Reporting health using the OnHealthCheck callback.
456214 [Thread Pool Worker] INFO Aws.GameLift.Server.ServerState (null) - Received TRUE from the onHealthCheck callback. Reporting process as healthy.
456218 [Thread Pool Worker] INFO Aws.GameLift.Server.GameLiftWebSocket (null) - Sending message to GameLift: {"HealthStatus":true,"Action":"HeartbeatServerProcess","RequestId":"4313deab-a463-4b94-9ade-d20ada387360"}
456266 [Thread Pool Worker] INFO Aws.GameLift.Server.GameLiftWebSocket (null) - Received HeartbeatServerProcess for GameLift with status 200. Data: {"Action":"HeartbeatServerProcess","RequestId":"4313deab-a463-4b94-9ade-d20ada387360","StatusCode":200}
Game Server: On client connected (connection index 0)
Game Server: Sending auth request to client (connection index 0)
Game Server: Received auth response from client (connection index 0)
Game Server:   - GameLift player session id: psess-fafb96c8-1451-4868-8efd-2c425805ad34
483833 [1] INFO Aws.GameLift.Server.GameLiftWebSocket (null) - Sending message to GameLift: {"GameSessionId":"arn:aws:gamelift:eu-west-1::gamesession/fleet-fe149927-5e37-458f-a957-8b050b7f76bf/gsess-b6fcb2bb-18a8-499f-aae8-806beb0231b5","PlayerSessionId":"psess-fafb96c8-1451-4868-8efd-2c425805ad34","Action":"AcceptPlayerSession","RequestId":"819cd0c6-25e1-44f8-b948-cc00c50fb547"}
Game Server: GameLiftServerSDK.AcceptPlayerSession() successful (connection index 0)
483893 [Thread Pool Worker] INFO Aws.GameLift.Server.GameLiftWebSocket (null) - Received AcceptPlayerSession for GameLift with status 200. Data: {"Action":"AcceptPlayerSession","RequestId":"819cd0c6-25e1-44f8-b948-cc00c50fb547","StatusCode":200}
483893 [Thread Pool Worker] DEBUG Aws.GameLift.Server.GameLiftWebSocketRequestHandler (null) - Request 819cd0c6-25e1-44f8-b948-cc00c50fb547 already removed.
483893 [Thread Pool Worker] DEBUG Aws.GameLift.Server.GameLiftWebSocketRequestHandler (null) - No promise found for request 819cd0c6-25e1-44f8-b948-cc00c50fb547.
Game Server: On client disconnected (connection index 0)
493246 [1] INFO Aws.GameLift.Server.GameLiftWebSocket (null) - Sending message to GameLift: {"GameSessionId":"arn:aws:gamelift:eu-west-1::gamesession/fleet-fe149927-5e37-458f-a957-8b050b7f76bf/gsess-b6fcb2bb-18a8-499f-aae8-806beb0231b5","PlayerSessionId":"psess-fafb96c8-1451-4868-8efd-2c425805ad34","Action":"RemovePlayerSession","RequestId":"e8777286-65dd-44d1-9179-1f3d9529321a"}
493303 [Thread Pool Worker] INFO Aws.GameLift.Server.GameLiftWebSocket (null) - Received RemovePlayerSession for GameLift with status 200. Data: {"Action":"RemovePlayerSession","RequestId":"e8777286-65dd-44d1-9179-1f3d9529321a","StatusCode":200}
493303 [Thread Pool Worker] DEBUG Aws.GameLift.Server.GameLiftWebSocketRequestHandler (null) - Request e8777286-65dd-44d1-9179-1f3d9529321a already removed.
493303 [Thread Pool Worker] DEBUG Aws.GameLift.Server.GameLiftWebSocketRequestHandler (null) - No promise found for request e8777286-65dd-44d1-9179-1f3d9529321a.
Game Server: On client connected (connection index 1)
Game Server: Sending auth request to client (connection index 1)
Game Server: Received auth response from client (connection index 1)
Game Server:   - GameLift player session id: psess-fafb96c8-1451-4868-8efd-2c425805ad34
494760 [1] INFO Aws.GameLift.Server.GameLiftWebSocket (null) - Sending message to GameLift: {"GameSessionId":"arn:aws:gamelift:eu-west-1::gamesession/fleet-fe149927-5e37-458f-a957-8b050b7f76bf/gsess-b6fcb2bb-18a8-499f-aae8-806beb0231b5","PlayerSessionId":"psess-fafb96c8-1451-4868-8efd-2c425805ad34","Action":"AcceptPlayerSession","RequestId":"278c1c6f-d6da-4fcc-87d3-95cb12aa4ef4"}
Game Server: GameLiftServerSDK.AcceptPlayerSession() successful (connection index 1)
494815 [Thread Pool Worker] INFO Aws.GameLift.Server.GameLiftWebSocket (null) - Received AcceptPlayerSession for GameLift with status 400. Data: {"Action":"AcceptPlayerSession","RequestId":"278c1c6f-d6da-4fcc-87d3-95cb12aa4ef4","StatusCode":400,"ErrorMessage":"InvalidPlayerSessionStatusException: PlayerSession (fafb96c8-1451-4868-8efd-2c425805ad34) has a status of COMPLETED instead of RESERVED"}
494815 [Thread Pool Worker] WARN Aws.GameLift.Server.GameLiftWebSocket (null) - Received unsuccessful status code 400 for request 278c1c6f-d6da-4fcc-87d3-95cb12aa4ef4 with message 'InvalidPlayerSessionStatusException: PlayerSession (fafb96c8-1451-4868-8efd-2c425805ad34) has a status of COMPLETED instead of RESERVED'
494816 [Thread Pool Worker] DEBUG Aws.GameLift.Server.GameLiftWebSocketRequestHandler (null) - Request 278c1c6f-d6da-4fcc-87d3-95cb12aa4ef4 already removed.
494816 [Thread Pool Worker] DEBUG Aws.GameLift.Server.GameLiftWebSocketRequestHandler (null) - No promise found for request 278c1c6f-d6da-4fcc-87d3-95cb12aa4ef4.
Game Server: On client disconnected (connection index 1)
```

In the log you can see two subsequent client connections. Both are authenticated successfully, despite the second one is using an outdated player session. GameLift event logs the faulty response (status code 400) but still returns `true` from `AcceptPlayerSession()`.

I've seen 2 old posts (3 and 5 years old) of similar reports, and wondered if this is still a standing issue?

Answer

Hey there! In the scenario with **Amazon GameLift**, it starts when you try to confirm a player's session, aiming to switch their status from `RESERVED` to `ACTIVE`. This ensures that the player is ready for the game. If a player leaves, their status shifts to `COMPLETED`, a change that's acknowledged by **GameLift**, even if you don't get a direct confirmation from it.

The twist in the tale comes when you, using the same player session ID, attempt to accept the player session again, thinking it's still in the` RESERVED` state. However, it turns out the status had already been updated to `COMPLETED`. This leads to an `InvalidPlayerSessionStatusException`.

Status – The status of the player session. The following are possible statuses:

* Reserved – Player session has been reserved, but the players isn't connected.
* Active – Player session is connected to the game server.
* Completed – Player session has ended; player is no longer connected.
* Timed Out – Player failed to connect.

When a player session is marked as `COMPLETED`, you will need to generate a new player session. I am currently looking into why your Game Server incorrectly marked the `AcceptPlayerSession` as successful when it was already set to `COMPLETED`.

#### Resources:
* [Player Session](https://docs.aws.amazon.com/gamelift/latest/developerguide/integration-server-sdk5-csharp-datatypes.html#integration-server-sdk5-csharp-datatypes-playersession)
* [AcceptPlayerSession](https://docs.aws.amazon.com/gamelift/latest/developerguide/integration-server-sdk5-csharp-actions.html#integration-server-sdk5-csharp-acceptplayersession)
* [Player Session Details](https://docs.aws.amazon.com/gamelift/latest/developerguide/gamelift-console-game-player-sessions-metrics.html#player-sessions)

GameLiftServerAPI.AcceptPlayerSession() always returns true

Resources:

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