UE 5.5 - Online Subsystem 'Join Session' always results in `On Failure`

SeiHanayou
Fri, 15 Nov 2024 19:27:09 +0000
Programming & Scripting

I’m developing a multiplayer game primarily in Blueprints, and am using the ‘Advanced Sessions’ and ‘Advanced Steam Sessions’ plugins (though my issue does not appear to be with these at all, but rather the engine’s built in Join Session functionality).

When developing in the editor, I can run two standalone clients on the same machine, and the session creation, finding, and joining all works flawlessly. While this does popup the Steam context window, I appreciate that this doesn’t utilise Steams backend, I’m mostly just using this to test game logic/replication.

I packaged a ‘development’ build of the game and have been having a few friends help me test. All of us can create an ‘Advanced Session’ no problem, and the ‘Find Advanced Sessions’ node also brings back our specific game sessions, so I’m confident that sessions are being created and exposed through Steam correctly. However, when attempting to join the sessions using the engine’s built in ‘Join Session’ node, it always ends up Failing (very explicity down the failure outcome).

There’s nothing to note in the logs (pasted below) per se except the second line from the bottom LogOnlineSession: Warning: STEAM: [FOnlineSessionSteam::JoinSession] The values of FOnlineSessionSettings::bUsesPresence and FOnlineSessionSettings::bUseLobbiesIfAvailable are treated as equal and have to match, however both bUseLobbiiesIfAvailable and bUsesPresence are set to true when the session is created.

Checked Common Issues

I’ve triple checked all the common debug steps:

Steam sockets is off (known to cause issues in recent UE versions), and all relevant Steam/Subsystem plugins are on

Host opens level with ‘listen’ param

AppId is 480 (and this clear works as session creation and session search UI have no issues)

I’ve set my download region to match my friends (prior to this I didn’t find any session results, as expected)

My EngineDefaut.ini is as per Unreal’s latest docs

I’ve manually added a steam_appid.txt with 480 inside to the build output folder (next to the .exe) as it didn’t seem to automatically generate this and I previously got errors for Steam not correctly initialising without this.

(Please forgive my debugging spaghetti)

Create Session

Find Sessions
(It’s cut off, but I extract all of the information to the UI when succesful)

Join Session:

(This Always ends up down the On Failure branch)

Logs

[2024.11.15-15.08.57:182][331]LogOnlineSession: STEAM: Found 1 lobbies, finalizing the search
[2024.11.15-15.08.57:182][331]LogOnlineSession: STEAM: Search result 0: LobbyId=Lobby[0x1860000A22CDCF5], LobbyId.IsValid()=true, CSteamID(LobbyId).IsLobby()=true
[2024.11.15-15.08.57:183][331]LogScript: Script Msg: Found a session. Ping is 9999
[2024.11.15-15.08.59:779][272]LogOnlineSession: Warning: STEAM: Server response IP:217.17.82.149
[2024.11.15-15.08.59:779][272]LogOnlineSession: Warning: STEAM: Removed incompatible build: ServerBuildUniqueId = 0x00000000, GetBuildUniqueId() = 0x023ecee6
[2024.11.15-15.09.00:067][375]LogOnlineSession: Warning: STEAM: Server response IP:76.139.168.52
[2024.11.15-15.09.00:067][375]LogOnlineSession: Warning: STEAM: Removed incompatible build: ServerBuildUniqueId = 0x00000000, GetBuildUniqueId() = 0x023ecee6
[2024.11.15-15.09.00:108][391]LogOnlineSession: Warning: STEAM: Server response IP:3.21.236.47
[2024.11.15-15.09.00:108][391]LogOnlineSession: Warning: STEAM: Removed incompatible build: ServerBuildUniqueId = 0x00000000, GetBuildUniqueId() = 0x023ecee6
[2024.11.15-15.09.01:740][985]LogOnlineSession: Warning: STEAM: Failed to respond IP:84.14.105.229
[2024.11.15-15.09.01:740][985]LogOnlineSession: Warning: STEAM: Failed to respond IP:118.31.223.0
[2024.11.15-15.09.01:740][985]LogOnlineSession: Warning: STEAM: Failed to respond IP:134.17.6.4
[2024.11.15-15.09.01:743][985]LogBlueprintUserMessages: [W_MainMenu_C_2147482250] Success! Found 1 sessions
[2024.11.15-15.09.01:743][985]LogBlueprintUserMessages: [W_MainMenu_C_2147482250] Hanayou
[2024.11.15-15.09.01:743][985]LogBlueprintUserMessages: [W_MainMenu_C_2147482250] Joining Session...
[2024.11.15-15.09.03:743][712]LogBlueprintUserMessages: [W_MainMenu_C_2147482250] 109775243638004981
[2024.11.15-15.09.03:744][712]LogOnlineSession: Warning: STEAM: [FOnlineSessionSteam::JoinSession] The values of FOnlineSessionSettings::bUsesPresence and FOnlineSessionSettings::bUseLobbiesIfAvailable are treated as equal and have to match
[2024.11.15-15.09.03:744][712]LogBlueprintUserMessages: [BP_GameInstance_C_2147482572] Server Join Failed

DefaultEngine.ini

[/Script/Engine.GameEngine]
+NetDriverDefinitions=(DefName="GameNetDriver",DriverClassName="OnlineSubsystemSteam.SteamNetDriver",DriverClassNameFallback="OnlineSubsystemUtils.IpNetDriver")

[OnlineSubsystem]
DefaultPlatformService=Steam

[OnlineSubsystemSteam]
bEnabled=true
SteamDevAppId=480

; If using Sessions
; bInitServerOnClient=true

[/Script/OnlineSubsystemSteam.SteamNetDriver]
NetConnectionClassName="OnlineSubsystemSteam.SteamNetConnection"

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